Can't say I've ever had a car test driven when i've part exchanged one but maybe this one will. last car i sold was to we buy any car they didn't even bother looking at it properly otherwise they would of seen the engine warning light.

Ive had a couple of my px's not only test driven but also subject to a mechanic's albeit brief inspection. Mainly at BMW franchises but also your run o the mill Vauxhall dealership.

Ive seen a few posts in HJ's column when it was freely available of people doing px's and after the deal was done, the dealer finding some fault with the car.

If your car's in good nick, nothing to be bothered about imho.

If trading in a fairly new car, a largely visual inspection, warning lights and engine start would normally suffice - the car will have been driven to the dealer. Older cars may come with some real risk of major defects.

Very simply the garage has sold you a car and is receiving payment from the finance company. I assume they are making a profit for this bit of the transaction

The garage has also agreed to pay outstanding finance on the trade in. What is not clear is by how much the market value of the trade in is above the outstanding finance.

The garage may simply send the trade in to auction were they will have a fairly informed view of the likely price. Or they may accept any residual risk on the basis that they are making sufficient profit on the deal anyway.

I try and run my cars into the ground so at least two have gone directly to a dismantler. Even then, in one case, it was checked to ensure it could move in forward and reverse under its own power.

When I traded our first Berlingo in2015 it was 10 years old and had 150k miles on it. Way off territory where it might go on a franchise dealer's forecourt - it was always going to auction.

Both prospective deals, a C3 Picasso or a Skoda Roomster, offered same price - a few hundred. Both took it round the block but only to ascertain the gears etc worked. Last time I checked it was still live and MoT'd.

A runner with 6 mths MoT can fetch £1000 /£1500 in a back street dealer. Might have been an idea to try & sell it rather than taking " a few hundred" even with 150k on the clock

Ideally I'd have kept it to 200k. Was changing reluctantly because it was becoming a money pit. Clutch, alternator, exhaust and valve clearances (a 'feature' of the XUD engine and its derivatives) had all needed attention. Just when I thought I was on level ground it developed a 'stiffness' in the steering and the cabin blower fan went intermittent.

In the circumstances I'd not got the commitment or patience to try and hawk it on E Bay or wherever. Time was at issue too.