First, we asked fuel economy expert Peter de Nayer to measure the real-world economy of our readers' old cars and new equivalents, so we could work out possible fuel savings.
The RAC mechanically inspected the old cars to check for any serious faults so we could find out how much it would cost to fix them.
We also put the old and new cars through their paces in a series of performance tests.
See below for details of the experts we used to undertake the economy, performance and mechanical tests on our scrappage contenders.
Job Vehicle examining engineer for the RAC
Ron assessed the condition of our readers' cars for us. He thoroughly checked the car's mechanicals, including the engine, brakes, steering and suspension.
RAC inspections start at £132. Log on to www.rac.co.uk/vehicle-checks
or call 0800 085 2529 for more information.
Job What Car? fuel economy expert
Is your old car drinking more fuel than it was when new? Would a brand-new car really save you money at the pumps? Peter spent 35 years testing
the real-world fuel economy of cars with the AA, so he was the man ideally placed to provide the answers.
Job What Car? consumer reporter
Will put our readers' old and new cars through their paces in a series of performance tests, in order to find out the effect of age and high mileages on acceleration and braking - and whether the equivalent new cars really are that much better at either.