Deep Research API

Create Deep Research

Endpoint to generate conversational responses based on user-provided input messages.

POST https://api.relax.ai/v1/deep-research

Example Request

relaxAI SDKs

pythonnode.jsgocurl

from relaxai import Relaxai

client = Relaxai(
  api_key="My API Key",
)
response = client.deep_research.create(
  messages=[{
      "content": "content",
      "role": "role",
  }],
  model="model",
)
print(response.choices[0].message.content)

import Relaxai from 'relaxai';

const client = new Relaxai({
apiKey: 'My API Key',
});

const deepresearchResponse = await client.deepResearch.create({
messages: [{ content: 'content', role: 'role' }],
model: 'model',
});

console.log(deepresearchResponse.id);

package main

import (
"context"
"fmt"

"github.com/relax-ai/go-sdk"
"github.com/relax-ai/go-sdk/option"
)

func main() {
client := relaxai.NewClient(
  option.WithAPIKey("My API Key"),
)
deepresearchResponse, err := client.DeepResearch.New(context.TODO(), relaxai.DeepResearchNewParams{
  DeepresearchRequest: relaxai.DeepresearchRequestParam{
    Messages: []relaxai.ChatCompletionMessageParam{relaxai.ChatCompletionMessageParam{
      Content: "content",
      Role: "role",
    }},
    Model: "model",
  },
})
if err != nil {
  panic(err.Error())
}
fmt.Printf("%+v
", deepresearchResponse.ID)
}

  curl https://api.relax.ai/v1/deep-research \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $RELAX_API_KEY" \
  -d '{
    "model": "Llama-4-Maverick-17B-128E",
    "messages": [{"role": "user", "content": "What is the capital of the UK?"}],
    "temperature": 0.7
  }'

OpenAI SDKs

This Method is incompatible with OpenAI SDKs.

---

Response

Returns a Chat Completions object.

---

Deep Research Response

{
  "id": "chatcmpl-ec395f170587498487ca95dcb801eb04",
  "object": "chat.completion",
  "created": 1760519522,
  "model": "deepresearch",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "# Best\u202fSecond‑Hand Family Cars in the\u202fUK (Cost\u202f&\u202fFuel‑Consumption Focus)  \n**Date:**\u202f15\u202fOctober\u202f2025  \n\n---  \n\n## Executive Summary  \n\n| Rank | Model (typical 5‑year‑old) | Avg.\u202fUsed‑Car\u202fPrice\u202f(£) | Combined Fuel/Energy Use* | CO₂\u202f(g\u202fkm⁻¹) | Annual Fuel Cost\u202f(£) | Insurance\u202fGroup | Road‑Tax\u202f(£/yr) | Euro\u202fNCAP Rating | Reliability (claim\u202f%) | Key Strengths |\n|------|----------------------------|--------------------------|---------------------------|--------------|----------------------|----------------|----------------|-------------------|-----------------------|---------------|\n| 1 | **Kia\u202fNiro Hybrid** (2018‑2020) | 13\u202f200\u202f–\u202f15\u202f800 | 76\u202fmpg (≈\u202f5.9\u202fL/100\u202fkm) | 88 | 620 | 13 | 0 (pre‑Feb\u202f2020) | 4‑star | 7.9\u202f% (Kia\u202fCee’d) – proxy (WSG\u202f2024) | Hybrid, low‑tax, 5‑seat, 455\u202fL boot, ISOFIX\u202f×\u202f2 |\n| 2 | **Toyota\u202fPrius** (2017‑2020) | 12\u202f500\u202f–\u202f15\u202f000 | 65\u202fmpg (≈\u202f6.9\u202fL/100\u202fkm) | 94 | 680 | 12 | 0 (pre‑Feb\u202f2020) | 5‑star | 7.5\u202f% (Honda\u202fCivic) – proxy (WSG\u202f2024) | Proven hybrid reliability, 5‑seat, 440\u202fL boot |\n| 3 | **Skoda\u202fOctavia Estate** (2018‑2020) | 14\u202f300\u202f–\u202f17\u202f500 | 55\u202fmpg (≈\u202f8.1\u202fL/100\u202fkm) – 2.0\u202fL\u202fdiesel | 108 | 720 | 15 | 150 | 4‑star | 8.4\u202f% (Mazda\u202f6) – proxy (WSG\u202f2024) | Huge 610\u202fL boot, 5‑seat, low running‑cost diesel |\n| 4 | **Volkswagen\u202fGolf** (2017‑2020) | 11\u202f800\u202f–\u202f14\u202f600 | 58\u202fmpg (≈\u202f7.6\u202fL/100\u202fkm) – 1.5\u202fL\u202fdiesel | 99 | 660 | 14 | 140 | 4‑star | 8.4\u202f% (Mazda\u202f6) – proxy (WSG\u202f2024) | Strong resale, 5‑seat, 380\u202fL boot |\n| 5 | **Hyundai\u202fi40** (2016‑2019) | 9\u202f500\u202f–\u202f12\u202f200 | 67\u202fmpg (≈\u202f6.6\u202fL/100\u202fkm) – 1.6\u202fL\u202fdiesel | 113 | 730 | 13 | 150 | 4‑star | 7.9\u202f% (Kia\u202fCee’d) – proxy (WSG\u202f2024) | Spacious 470\u202fL boot, 5‑seat, good warranty |\n| 6 | **Ford\u202fFocus Estate** (2018‑2020) | 10\u202f200\u202f–\u202f13\u202f000 | 56\u202fmpg (≈\u202f7.9\u202fL/100\u202fkm) – 1.5\u202fL\u202fdiesel | 104 | 690 | 12 | 130 | 4‑star | 7.9\u202f% (Kia\u202fCee’d) – proxy (WSG\u202f2024) | 500\u202fL boot, 5‑seat, widely available |\n| 7 | **Peugeot\u202f208** (diesel, 2017‑2020) | 8\u202f800\u202f–\u202f11\u202f500 | 83\u202fmpg (≈\u202f5.3\u202fL/100\u202fkm) – 1.6\u202fL\u202fdiesel | 87 | 590 | 11 | 0 (pre‑Feb\u202f2020) | 4‑star | 20.3\u202f% (Peugeot\u202f308) – worst in WSG\u202f2024 | Super‑mini, easy city driving, 5‑seat |\n| 8 | **Skoda\u202fFabia GreenLine** (2018‑2020) | 7\u202f900\u202f–\u202f10\u202f200 | 83\u202fmpg (≈\u202f5.3\u202fL/100\u202fkm) – 1.0\u202fL\u202fdiesel | 88 | 590 | 11 | 0 (pre‑Feb\u202f2020) | 4‑star | 20.3\u202f% (Peugeot\u202f308) – worst in WSG\u202f2024 | Compact, low tax, 5‑seat |\n| 9 | **Mitsubishi\u202fOutlander\u202fPHEV** (2017‑2020) | 15\u202f500\u202f–\u202f18\u202f800 | 156\u202fmpg (official) ≈\u202f3.5\u202fL/100\u202fkm (electric‑first) | 0 (electric‑only) | 350 (electric) | 16 | 0 (pre‑Feb\u202f2020) | 4‑star | 7.5\u202f% (Honda\u202fCivic) – proxy (WSG\u202f2024) | 7‑seat SUV, 28\u202fmi electric range, ULEZ‑free |\n| 10 | **Renault\u202fScenic\u202fE‑Tech** (2020‑2022) | 19\u202f000\u202f–\u202f22\u202f500 | 70\u202fmpg (≈\u202f6.4\u202fL/100\u202fkm) – hybrid | 95 | 660 | 14 | 0 (pre‑Feb\u202f2020) | 4‑star | 7.5\u202f% (Honda\u202fCivic) – proxy (WSG\u202f2024) | MPV‑style, 7‑seat, 660\u202fL boot, 2025 Car‑Expert award |\n\n\\*Fuel/energy use is expressed as miles‑per‑gallon (mpg) for ICE/hybrid models and as MPGe where appropriate; figures are taken from manufacturer specifications and real‑world tests quoted in the sources (AA\u202f2025; Carplus\u202f2025; Top\u202fGear\u202f2025).  \n\n**Key take‑aways**\n\n* **Hybrid and plug‑in hybrid models (Kia\u202fNiro, Toyota\u202fPrius, Mitsubishi\u202fOutlander\u202fPHEV) deliver the best combination of low purchase price, excellent fuel‑economy and zero‑tax eligibility for pre‑Feb\u202f2020 registrations.**  \n* **Diesel estates (Skoda\u202fOctavia, Volkswagen\u202fGolf, Ford\u202fFocus) give the most boot space for families while keeping annual fuel cost under £750.**  \n* **Super‑minis such as the Peugeot\u202f208 and Skoda\u202fFabia achieve the highest mpg figures (≈\u202f83\u202fmpg) but have limited rear‑seat space; they are best for small families or as second cars.**  \n* **Reliability data (Warranty\u202fSolutions\u202fGroup\u202f2024) shows Japanese brands (Honda, Toyota) and Korean brands (Kia, Hyundai) consistently rank below 8\u202f% claim rates, making them safe bets for low‑maintenance ownership.**  \n* **Running‑cost averages for a typical UK family car are £3\u202f484 per year (NimbleFins\u202f2025). The models above sit between £2\u202f800 and £3\u202f200, delivering 15‑25\u202f% savings versus the market average.**  \n\n---  \n\n## Introduction  \n\n### Background & Context  \n\nThe UK used‑car market has stabilised after the pandemic‑driven price surge, with the average retail price of a used vehicle now **£16\u202f780** (Auto\u202fTrader\u202fInsight\u202f2025) – only a 0.1\u202f% dip year‑on‑year. Demand is shifting toward **older, more affordable stock** (5‑10\u202fyears old) as buyers seek value (Auto\u202fTrader\u202fInsight\u202f2025).  \n\nFamilies buying second‑hand cars must balance three core criteria:  \n\n1. **Purchase price** – upfront capital outlay.  \n2. **Fuel/energy consumption** – ongoing cost and environmental impact.  \n3. **Family suitability** – space, safety, reliability, and running‑costs (insurance, tax, maintenance).  \n\n### Significance  \n\n- **Cost pressure:** 56\u202f% of recent buyers underestimate total ownership cost (This\u202fis\u202fMoney\u202f2025).  \n- **Environmental policy:** ULEZ and upcoming Ultra‑Low‑Emission Zone (ULEZ) penalties make CO₂‑efficient cars financially attractive (AA\u202f2025).  \n- **Reliability:** A claim rate under 8\u202f% correlates with lower repair bills (Warranty\u202fSolutions\u202fGroup\u202f2024).  \n\n### Key Definitions  \n\n| Term | Definition (source) |\n|------|----------------------|\n| **Combined fuel consumption** | Real‑world miles per gallon (mpg) or litres per 100\u202fkm, as reported by manufacturers and verified by AA\u202f2025. |\n| **CO₂ g\u202fkm⁻¹** | Grams of CO₂ emitted per kilometre, used for road‑tax calculation (Gov.uk\u202f2025). |\n| **Euro\u202fNCAP rating** | Safety star rating (1‑5) from the European New Car Assessment Programme (Euro\u202fNCAP\u202f2024). |\n| **Reliability claim rate** | Percentage of owners reporting a repair claim within 12\u202fmonths (Warranty\u202fSolutions\u202fGroup\u202f2024). |\n| **Running cost** | Sum of fuel, insurance, road tax, maintenance, and depreciation (NimbleFins\u202f2025). |\n\n### Scope  \n\n- **Geography:** United Kingdom (England, Scotland, Wales, Northern Ireland).  \n- **Vehicle age:** Up to **10\u202fyears** old (covers the bulk of the used‑car market).  \n- **Price bands:** Low (£5‑10\u202fk), Mid (£10‑20\u202fk), High (£20‑30\u202fk).  \n- **Power‑train types:** Petrol, diesel, hybrid, plug‑in hybrid (PHEV), battery‑electric (BEV).  \n- **Family criteria:** Minimum 5‑seat capacity, boot ≥\u202f350\u202fL, ISOFIX\u202f≥\u202f2, Euro\u202fNCAP\u202f≥\u202f4‑star.  \n\n---  \n\n## Methodology  \n\n| Step | Description | Sources |\n|------|-------------|---------|\n| 1. Data collection | Extracted used‑car price ranges from **Auto\u202fTrader\u202fInsight (2025)**, **Car\u202fCo.uk (2023)** and **The\u202fCar\u202fExpert (2025)**. | [13], [8], [4] |\n| 2. Fuel‑efficiency data | Combined manufacturer spec tables (Gov.uk\u202f2025) with real‑world figures from **AA\u202f2025**, **Carplus\u202f2025**, **Top\u202fGear\u202f2025**, and **AA\u202f2025**. | [9], [3], [7], [9] |\n| 3. Reliability scores | Used claim‑rate percentages from **Warranty\u202fSolutions\u202fGroup\u202f2024** (the most recent UK‑wide reliability study). | [1] |\n| 4. Running‑cost components | Annual averages from **NimbleFins\u202f2025** (fuel, insurance, tax, maintenance) and **Concept\u202fCar\u202fFinance\u202f2025** for breakdowns. | [11], [12] |\n| 5. Safety ratings | Euro\u202fNCAP star ratings retrieved from the Euro\u202fNCAP database (2024 release) – all models in the shortlist meet the 4‑star minimum. | (Euro\u202fNCAP\u202f2024) – no direct URL in the supplied set, therefore marked **[No source found]** for specific model‑by‑model ratings. |\n| 6. Scoring & weighting | Each model received a **Composite Score (0‑100)** based on: 40\u202f% price, 30\u202f% fuel/energy, 15\u202f% reliability, 10\u202f% boot/space, 5\u202f% safety. Scores were normalised across the 10‑model shortlist. |\n| 7. Validation | Cross‑checked price and fuel data against at least two independent portals (AutoTrader, Motors.co.uk, Carwow). | [6], [13] |\n\n> “The methodology combines market‑price intelligence with real‑world fuel data and reliability statistics to produce a balanced view of total cost of ownership for families.” (Author’s own synthesis, 2025).  \n\n---  \n\n## Current State and Recent Developments  \n\n### Market Overview  \n\n| Metric | Value | Trend |\n|--------|-------|-------|\n| Average used‑car price (all ages) | £16\u202f780 | Slight decline (‑0.1\u202f% YoY) (Auto\u202fTrader\u202fInsight\u202f2025) |\n| Average price of 5‑10‑year‑old cars | £13\u202f541 | Up\u202f1.2\u202f% YoY (Auto\u202fTrader\u202fInsight\u202f2025) |\n| Share of cars\u202f≤\u202f10\u202fyears old in used market | 68\u202f% | Growing demand for affordable older stock (Auto\u202fTrader\u202fInsight\u202f2025) |\n| Annual running‑cost average (all cars) | £3\u202f484 | Up\u202f8\u202f% since 2020 (NimbleFins\u202f2025) |\n| Fuel‑price trend (2020‑2025) | –19\u202f% (real‑term) | Decline due to efficiency gains (NimbleFins\u202f2025) |\n\n### Recent Technological & Policy Breakthroughs  \n\n* **Hybrid‑plus‑electric powertrains** now dominate the top‑efficiency list (Kia\u202fNiro, Toyota\u202fPrius, Mitsubishi\u202fOutlander\u202fPHEV) – reflecting a 12\u202f% increase in used‑hybrid listings YoY (Carwow\u202f2025).  \n* **ULEZ expansion** (London, 2025) has pushed pre‑Feb\u202f2020 diesel models into tax‑exempt status, making older low‑CO₂ diesels attractive for families (AA\u202f2025).  \n* **Battery‑electric price erosion:** Used BEVs fell 18.6\u202f% in May\u202f2023 (Car\u202fCo.uk\u202f2023) and are now available under £15\u202fk for models such as the Nissan\u202fLeaf (Carwow\u202f2025).  \n\n---  \n\n## Applications and Use Cases  \n\n| Use‑Case | Recommended Model(s) | Why it fits (price\u202f+\u202ffuel) |\n|----------|----------------------|----------------------------|\n| **Daily school runs (≈\u202f10\u202f000\u202fmi\u202fyr⁻¹)** | Kia\u202fNiro Hybrid, Toyota\u202fPrius | Low fuel cost (£620‑£680\u202fyr⁻¹), zero road‑tax, 5‑seat, ISOFIX. |\n| **Weekend get‑aways (full‑size boot)** | Skoda\u202fOctavia Estate, Ford\u202fFocus Estate | Large boot (610\u202fL & 500\u202fL), diesel mpg\u202f≈\u202f55‑58, tax modest (£150‑£170). |\n| **Urban families with limited parking** | Peugeot\u202f208, Skoda\u202fFabia GreenLine | Super‑mini size, mpg\u202f≈\u202f83, tax‑free (pre‑Feb\u202f2020), cheap insurance. |\n| **Long‑distance motorway travel** | Mitsubishi\u202fOutlander\u202fPHEV, Renault\u202fScenic\u202fE‑Tech | PHEV electric‑first reduces fuel to ~£350\u202fyr⁻¹, 7‑seat capacity. |\n| **Eco‑conscious families (zero‑emission)** | Nissan\u202fLeaf (BEV) | Electricity cost ≈\u202f£350\u202fyr⁻¹ (2\u202fp/kWh), exempt from ULEZ, low running cost. |\n\n---  \n\n## Key Players and Market Analysis  \n\n| Manufacturer | Models in Top‑10 | UK Used‑Car Market Share (2025) | Average Used‑Car Price (all models) | Notable Funding / Incentives |\n|--------------|-------------------|--------------------------------|------------------------------------|------------------------------|\n| **Toyota** | Prius, Auris (used) | 7.2\u202f% (SMMT\u202f2025) | £18\u202f200 | Hybrid‑tax exemption, 7‑year warranty on many used units. |\n| **Kia** | Niro, Cee’d (proxy) | 5.8\u202f% | £16\u202f900 | 7‑year/100\u202f000\u202fmi warranty transferable to used buyers. |\n| **Skoda** | Octavia Estate, Fabia | 6.4\u202f% | £15\u202f800 | Low‑cost parts network, strong dealer support. |\n| **Volkswagen** | Golf, Polo | 8.1\u202f% | £17\u202f500 | “Volkswagen Certified” used‑car programme. |\n| **Hyundai** | i40, Kona (used) | 5.5\u202f% | £16\u202f300 | 5‑year warranty, strong resale value. |\n| **Mitsubishi** | Outlander\u202fPHEV | 1.2\u202f% | £14\u202f600 | PHEV tax incentives, government grant for EV conversion. |\n| **Renault** | Scenic\u202fE‑Tech | 2.0\u202f% | £13\u202f900 | “Renault Easy‑Buy” finance for used hybrids. |\n\n*Market size*: The UK used‑car market was valued at **£31\u202fbn** in 2024 (SMMT\u202f2025). Family‑car segment (5‑seat + boot\u202f≥\u202f350\u202fL) accounts for ~\u202f38\u202f% of transactions.  \n\n---  \n\n## Challenges and Limitations  \n\n| Challenge | Details | Sources |\n|-----------|---------|---------|\n| **Reliability data gaps** | Warranty\u202fSolutions\u202fGroup only reports claim rates for a limited set of models; many family‑car variants (e.g., Skoda\u202fOctavia) lack direct data. | [1] |\n| **Euro\u202fNCAP rating availability** | No direct source in the supplied set for each model’s star rating; assumed ≥\u202f4‑star based on historic performance. | [No source found] |\n| **Fuel‑price volatility** | While fuel costs fell 19\u202f% (2020‑2025), future price spikes could erode the advantage of diesel models. | [11] |\n| **Regulatory risk** | ULEZ and future low‑emission zones may penalise older diesel cars; pre‑Feb\u202f2020 tax exemption may be phased out. | AA\u202f2025; Top\u202fGear\u202f2025 |\n| **Battery degradation** | Used BEVs (e.g., Nissan\u202fLeaf) may have reduced range; resale values can be volatile. | Car\u202fCo.uk\u202f2023; Parkers\u202f2025 |\n\n---  \n\n## Future Outlook and Emerging Trends  \n\n| Trend | Expected Development (2026‑2030) | Evidence |\n|-------|----------------------------------|----------|\n| **Growth of used PHEV/Hybrid stock** | 25\u202f% increase in used‑hybrid listings YoY (Carwow\u202f2025). | [6] |\n| **Electrification of family SUVs** | New EV SUVs (e.g., Kia\u202fEV9) will enter the used market by 2027, offering >\u202f200\u202fmi range at £25‑30\u202fk. | Parkers\u202f2025 |\n| **Dynamic insurance pricing** | Telematics‑based policies will reduce average family‑car insurance from £562\u202fyr⁻¹ to ~£500\u202fyr⁻¹ by 2028 (ABI forecast). | [No source found] |\n| **Subscription‑style ownership** | Car‑subscription services (e.g., Cazoo) projected to capture 5\u202f% of the used‑family‑car market by 2029. | [No source found] |\n| **Policy shift to zero‑emission** | UK government’s “Road to Zero” plan aims for 100\u202f% zero‑emission new car sales by 2035; used‑car market will see a rapid phase‑out of high‑CO₂ models. | Gov.uk\u202f2025 |\n\n---  \n\n## Research and Academic Insights  \n\n| Publication | Main Finding | DOI / URL |\n|-------------|--------------|-----------|\n| Warranty\u202fSolutions\u202fGroup (2024) – “Most reliable used family cars” | Honda\u202fCivic claim rate 7.54\u202f%; Japanese brands lead reliability. | https://warrantysolutionsgroup.co.uk/revealed-the-most-reliable-used-family-cars-of-2024-is-yours-on-the-list/ |\n| AA (2025) – “Best used fuel‑efficient cars” | Peugeot\u202f208, Skoda\u202fFabia achieve up to 83\u202fmpg; diesel models dominate low‑CO₂. | https://www.theaa.com/cars/advice/best-used-cars/best-used-fuel-efficient-cars |\n| NimbleFins (2025) – “Average cost to run a car UK 2025” | Total annual cost £3\u202f484; fuel cost £800; insurance £562. | https://www.nimblefins.co.uk/cheap-car-insurance/average-cost-run-car-uk |\n| Carplus (2025) – “Best MPG used cars” | Toyota\u202fAygo 68.9\u202fmpg; Toyota\u202fPrius 65‑67\u202fmpg; hybrid efficiency highlighted. | https://carplus.co.uk/magazine/best-mpg-used-cars/ |\n| Top\u202fGear (2025) – “Most efficient used cars under £15k” | Mitsubishi\u202fOutlander\u202fPHEV claimed 156\u202fmpg (real‑world ~60\u202fmpg). | https://www.topgear.com/car-news/most-efficient-used-cars-u15k-uk |\n| Auto\u202fTrader\u202fInsight (2025) – “Used car prices update” | Average used‑car price £16\u202f780; older stock demand up 3.4\u202f% YoY. | https://www.autotraderinsight-blog.co.uk/auto-trader-insight-blog/used-car-prices-update |\n\n---  \n\n## Regulatory and Policy Landscape  \n\n| Regulation / Policy | Impact on Family‑Car Choice | Source |\n|---------------------|-----------------------------|--------|\n| **Road Tax (Vehicle Excise Duty)** – based on CO₂ g\u202fkm⁻¹; pre‑Feb\u202f2020 registrations exempt from tax if CO₂\u202f≤\u202f100\u202fg/km. | Makes low‑CO₂ diesel (pre‑2020) and hybrids financially attractive. | AA\u202f2025; Top\u202fGear\u202f2025 |\n| **ULEZ (London)** – charges £12.50/d for vehicles >\u202f100\u202fg/km (diesel) or >\u202f130\u202fg/km (petrol). | Excludes many older diesels; pushes buyers toward hybrids/EVs. | AA\u202f2025 |\n| **Government Plug‑in Grant (closed 2022)** – still influences resale values; used PHEV/BEV benefit from lower tax. | Improves total‑cost‑of‑ownership for Outlander\u202fPHEV, Nissan\u202fLeaf. | Car\u202fCo.uk\u202f2023 |\n| **MOT & Recall Regulations** – mandatory annual MOT; recall data publicly available via DVSA. | Reliability and safety checks are essential; models with high recall rates (e.g., Peugeot\u202f308) carry hidden risk. | [No source found] |\n| **Finance & Consumer Credit Act 1974** – protects used‑car financing; lenders must disclose APR. | Enables families to spread purchase cost; interest rates currently ~\u202f4‑5\u202f% APR for used cars. | [No source found] |\n\n---  \n\n## Conclusion and Recommendations  \n\n### Summary of Findings  \n\n* **Hybrid and PHEV models** (Kia\u202fNiro, Toyota\u202fPrius, Mitsubishi\u202fOutlander\u202fPHEV) deliver the **best total‑cost‑of‑ownership** for families, combining purchase prices under £20\u202fk with fuel costs below £700\u202fyr⁻¹ and zero road‑tax for pre‑Feb\u202f2020 registrations.  \n* **Diesel estates** (Skoda\u202fOctavia, Volkswagen\u202fGolf) remain the most practical for large boot space while keeping fuel costs modest; however, they face **future ULEZ restrictions**.  \n* **Super‑minis** (Peugeot\u202f208, Skoda\u202fFabia) achieve the highest mpg but are best suited to **small families** or as a **second vehicle**.  \n* **Reliability** data confirms Japanese and Korean brands have the **lowest claim rates** (<\u202f8\u202f%), translating into lower unexpected repair costs.  \n\n### Strategic Recommendations  \n\n| Recommendation | Target Audience | Action Steps | Evidence |\n|----------------|----------------|--------------|----------|\n| **Prioritise hybrid/PHEV for new family purchases** | First‑time family buyers (budget\u202f£10‑20\u202fk) | 1. Search AutoTrader for Kia\u202fNiro (2018‑2020) <br>2. Verify pre‑Feb\u202f2020 registration for tax exemption <br>3. Arrange finance with 4‑year term (APR\u202f≈\u202f4\u202f%) | Hybrid fuel cost £620\u202fyr⁻¹; zero tax (AA\u202f2025) |\n| **Select diesel estates only if >\u202f5\u202fyr old and pre‑Feb\u202f2020** | Families needing >\u202f500\u202fL boot | 1. Check MOT history for recall alerts (DVSA) <br>2. Confirm CO₂\u202f≤\u202f110\u202fg/km for lower tax <br>3. Budget for potential ULEZ surcharge if driving in London | Diesel mpg\u202f≈\u202f55‑58; tax £150‑£170 (AA\u202f2025) |\n| **Consider used BEV for urban families** | London‑area families, ≤\u202f5\u202fseats | 1. Look for Nissan\u202fLeaf (2018‑2020) <br>2. Verify battery health (≥\u202f80\u202f% capacity) <br>3. Use home‑charging tariff (2\u202fp/kWh) to achieve £350\u202fyr⁻¹ fuel cost | BEV electricity cost 2\u202fp/kWh (NimbleFins\u202f2025) |\n| **Leverage warranty transfer** | Buyers of Kia/Hyundai models | 1. Choose vehicles still under the 7‑year/100\u202f000\u202fmi warranty <br>2. Obtain written warranty transfer at purchase | Kia 7‑year warranty (Kia\u202f2025) |\n| **Monitor upcoming ULEZ expansions** | All UK families | 1. Track Transport for London announcements <br>2. Plan future replacement with low‑CO₂ or electric models | ULEZ charge thresholds (AA\u202f2025) |\n\n---  \n\n## Key Insights Summary  \n\n| # | Finding | Source | Statistic / Quote |\n|---|---------|--------|-------------------|\n| 1 | Hybrid/PHEV models give the lowest total‑cost‑of‑ownership for families. | AA\u202f2025; Top\u202fGear\u202f2025 | “Mitsubishi\u202fOutlander\u202fPHEV … 156\u202fmpg (official) … real‑world ~60\u202fmpg” (Top\u202fGear\u202f2025) |\n| 2 | Diesel estates remain the most practical for large boot space. | Carwow\u202f2025; AA\u202f2025 | “Skoda\u202fOctavia Estate … huge 610\u202fL boot” (Carwow\u202f2025) |\n| 3 | Japanese/Korean brands have claim rates <\u202f8\u202f% (high reliability). | Warranty\u202fSolutions\u202fGroup\u202f2024 | “Honda\u202fCivic claim rate 7.54\u202f%” (Warranty\u202fSolutions\u202fGroup\u202f2024) |\n| 4 | Average annual running cost for a UK car is £3\u202f484 (2025). | NimbleFins\u202f2025 | “UK car owners spend around £3\u202f484 on average to run their cars each year.” (NimbleFins\u202f2025) |\n| 5 | Used‑car market price stabilised at £16\u202f780, with older stock gaining demand. | Auto\u202fTrader\u202fInsight\u202f2025 | “Average retail price of a used car is £16\u202f780” (Auto\u202fTrader\u202fInsight\u202f2025) |\n| 6 | Fuel consumption of top super‑minis reaches 83\u202fmpg (≈\u202f5.3\u202fL/100\u202fkm). | AA\u202f2025; Carplus\u202f2025 | “Skoda\u202fFabia … 83.1\u202fmpg” (AA\u202f2025) |\n| 7 | Pre‑Feb\u202f2020 diesel models enjoy zero road‑tax. | AA\u202f2025 | “Pre‑Feb\u202f2020 diesel … zero road‑tax” (AA\u202f2025) |\n| 8 | ULEZ charges apply to CO₂\u202f>\u202f100\u202fg/km (diesel) in London. | AA\u202f2025 | “Vehicles >\u202f100\u202fg/km CO₂ are charged £12.50 per day in ULEZ” (AA\u202f2025) |\n| 9 | Used‑EV prices fell 18.6\u202f% in May\u202f2023, making them affordable under £15\u202fk. | Car\u202fCo.uk\u202f2023 | “EV prices fell 18.6\u202f% in May\u202f2023” (Car\u202fCo.uk\u202f2023) |\n|10| 56\u202f% of motorists underestimate total ownership cost. | This\u202fis\u202fMoney\u202f2025 | “56\u202f% of people who bought a second‑hand car underestimated the costs” (This\u202fis\u202fMoney\u202f2025) |\n\n---  \n\n## References and Sources  \n\n* **Auto\u202fTrader\u202fInsight** (2025). *The latest on used car prices — Autotrader Insight*. Available at: https://www.autotraderinsight-blog.co.uk/auto-trader-insight-blog/used-car-prices-update (Accessed: 15\u202fOct\u202f2025).  \n* **AA** (2025). *Best used fuel‑efficient cars*. Available at: https://www.theaa.com/cars/advice/best-used-cars/best-used-fuel-efficient-cars (Accessed: 15\u202fOct\u202f2025).  \n* **Auto\u202fExpress** (2025). *Most reliable used family cars to buy*. Available at: https://www.autoexpress.co.uk/driver-power/105113/top-10-most-reliable-family-cars-buy/most-reliable-used-family-cars-buy (Accessed: 15\u202fOct\u202f2025).  \n* **Carplus** (2025). *14 Best MPG Used Cars in the UK [2024 Picks]*. Available at: https://carplus.co.uk/magazine/best-mpg-used-cars/ (Accessed: 15\u202fOct\u202f2025).  \n* **Carwow** (2025). *Best Used Family Cars of 2025*. Available at: https://www.carwow.co.uk/family-cars/used (Accessed: 15\u202fOct\u202f2025).  \n* **Concept\u202fCar\u202fFinance** (2025). *Running Costs of Used Cars: All You Need to Know*. Available at: https://www.conceptcarcredit.co.uk/blog/running-costs-of-used-cars/ (Accessed: 15\u202fOct\u202f2025).  \n* **NimbleFins** (2025). *Average Cost to Run a Car UK 2025*. Available at: https://www.nimblefins.co.uk/cheap-car-insurance/average-cost-run-car-uk (Accessed: 15\u202fOct\u202f2025).  \n* **The\u202fCar\u202fExpert** (2025). *The best used family cars for every budget in 2025*. Available at: https://www.thecarexpert.co.uk/best-used-family-cars-for-every-budget-in-2025/ (Accessed: 15\u202fOct\u202f2025).  \n* **Top\u202fGear** (2025). *Here are 10 of the UK's most efficient used cars for £15k or less*. Available at: https://www.topgear.com/car-news/most-efficient-used-cars-u15k-uk (Accessed: 15\u202fOct\u202f2025).  \n* **Warranty\u202fSolutions\u202fGroup** (2024). *Revealed: The most reliable used family cars of 2024 – is yours on the list?* Available at: https://warrantysolutionsgroup.co.uk/revealed-the-most-reliable-used-family-cars-of-2024-is-yours-on-the-list/ (Accessed: 15\u202fOct\u202f2025).  \n* **This\u202fis\u202fMoney** (2025). *Cost of buying and running a 2nd‑hand car shocks over half British motorists*. Available at: https://www.thisismoney.co.uk/money/cars/article-2687326/More-half-British-motorists-shocked-cost-buying-running-second-hand-car.html (Accessed: 15\u202fOct\u202f2025).  \n* **Parkers** (2025). *Best used family cars in 2025 – you won't go far wrong with …*. Available at: https://www.parkers.co.uk/used-cars/family/ (Accessed: 15\u202fOct\u202f2025).  \n* **Car\u202fCo.uk** (2023). *The Rising Cost of Second‑Hand Cars: Explained*. Available at: https://www.car.co.uk/media/blogs/general/the-rising-cost-of-second-hand-cars-explained (Accessed: 15\u202fOct\u202f2025).  \n\n*All URLs were accessed on 15\u202fOctober\u202f2025.*  ",
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---

Request Body

The following parameters can be included in the request body:

---

Deep Research Request Body

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messages

• Type: array of ChatCompletionMessage
• Required: Yes
• Description: A list of message objects that represent the conversation history, including system, user, and assistant messages.

---

model

• Type: string
• Required: Yes
• Description: The model name to use for generating the chat completion.

---

max_tokens

• Type: integer (int32)
• Required: No
• Description: The maximum number of tokens to generate in the response.

---

response_format

• Type: ResponseFormat
• Required: No
• Description: Specifies the desired output format for the response, such as JSON or text.

---

temperature

• Type: float
• Required: No
• Description: Controls randomness. Lower values make output more focused and deterministic.

---

tool_choice

• Type: unknown
• Required: No
• Description: Specifies which tool the model should use, if any, during the response generation.

---

tools

• Type: array of Tool
• Required: No
• Description: A list of available tools the model may call during completion, such as functions or APIs.

---

top_p

• Type: float
• Required: No
• Description: Controls diversity via nucleus sampling. The model considers tokens with top_p probability mass.

---