Are you in the market for a used car? Then these topical tips from CAR Magazine is worth the read before you make that expensive purchase. Beware of low mileages, especially on smaller or cheaper cars. It is always possible that the odometer has been turned back. Diesels are often bought because the driver needs to undertake long trips without consuming vast amounts of fuel. This could be a sales rep, or someone travelling large distances to work, lots of lengthy trips for family holidays, etc.