How to know the real value of your car before part-exchange
A dealer's part-exchange offer leans on two numbers you can find yourself. Here's how to use them to set a floor and walk out with a fair deal.
Published
The gap dealers rely on
A dealer will quote you a part-exchange price, then sell your car for roughly £1,500–£3,000 more. That gap funds warranty, prep and their margin. Fair enough — but the gap only stays reasonable if you know what the car should sell for retail. If you don't, the gap becomes two or three grand of invisible profit.
Step 1: Find the retail comparables
On WheelsAI, search your exact year, make, model and derivative, filter by ±10% mileage, and note the lowest five asking prices. The retail floor is roughly the second-lowest — the actual lowest is usually something with a problem.
Step 2: Back out to trade
Take the retail floor and subtract £1,500–£2,500 depending on age. Under three years old: £1,500. Three to seven years old: £2,000. Over seven, or under £5,000 retail: £2,500 because costs of prep don't scale down.
Step 3: Adjust for condition
Knock a further £200 for each real cosmetic issue (kerbed alloy, scuffed bumper corner, seat bolster wear). Add £300 if you have full main-dealer service history. Add £500 if the MOT has over 10 months left.
What 'getting a fair deal' looks like
You walk in with a number in your head. The dealer's first offer is £700 below it. You counter with your number and point at the comparables on WheelsAI on your phone. They come up £500. You agree at £200 under your number. Everyone got something.
The takeaway
Never accept the first part-exchange offer. Run the WheelsAI free valuation plus comparable search, set your floor, and negotiate from data — not from the dealer's whiteboard.
Frequently asked questions
Frequently asked questions
What if the dealer says my car is worth less than my number?
Ask them what they'd retail it for. Their answer tells you the gap. If the gap is under £2,500 you're close; if it's over £3,500 they're being greedy.
What about valuation websites like Parkers or AutoTrader's?
Use them as a second opinion, but they pull from national averages. Live WheelsAI comparables in your postcode are tighter.