New car buyers are able to choose exactly what equipment is fitted to their cars. But for used car buyers, the choice is limited to what's already on the market. Demand for some equipment is rising steadily: many supermini buyers now want power steering, while twin front airbags, ABS and air conditioning are all near the top of the shopping lists of motorists looking for family cars.

It makes sense to pick a used car that comes with most of the must-have equipment that new car buyers demand. Some day you're going to want to sell the car or trade it in. When that day comes, private buyers and motor traders alike will have higher expectations regarding the specification than they do today.

Apart from CD players, in-car entertainment (ICE) equipment has been omitted from our analysis of essential and desirable used car specs. Quite simply, a standard manufacturer-fitted radio/cassette/CD is good enough for most used car buyers. People who just have to have distortion-free, bass-balanced Dvorak or The Darkness are prepared to spend a lot on custom in-car systems - even though they'll never see their money back when they come to resell.

The table on the next page lists the most common items of standard and optional equipment fitted to cars in the past five years. Use it to assess whether possessing or lacking a certain feature is likely to have a positive or negative impact on the value and saleability of your used car choice.