WHAT kind of car do you really need? Do you have to have an estate? Does it really need to be a diesel?

These may seem like odd questions, but they are prompted by that most rational of things, the UsedCarExpert commitment to saving the canny buyer the greatest amount of money.

Recently we have noticed the price difference between cars that everybody wants (for example diesel estates) and cars that nobody really cares about (eg petrol saloons) growing ever bigger.

If you are prepared to be flexible about spec and trim, then huge savings can be made.

There is far less demand for unfashionable cars and the general rule of thumb is often to get the exact opposite from the car of the moment.

So if everybody wants a diesel estate go for a petrol saloon and save yourself a small fortune.

Consider the Mercedes C-Class. Launched in 2007 it is still a very desirable car - a genuine prestige executive motor with the best badge there is.

But the spread of prices on this model is amazing. With ‘desirable' variants retailing at many thousands more than the less immediately attractive cars.

The following three picks should indicate perfectly what we mean.

This is the car everybody wants. A re-sale silver Sport Estate, with the 2.2 diesel engine and automatic gearbox. A 2009 car, which has done 32,000 miles and is being sold by a prestige dealer group. It's really hard to find anything negative to say about this motor except for its very steep price - which is just under £16,000.

Same car, but with the excellent and extremely economical 1.6 supercharged petrol engine. This car is a 2010 model with just 20,000 miles on the clock and is on for £14,000. That's a £2,000 saving for a car with far fewer miles and a very tough engine and gearbox combination.

If you are happy to drive a saloon then this is the one to go for. It's a 1.6 supercharged model with Mercedes' excellent six-speed manual gearbox fitted. 25,000 miles on the clock at just £12,300. That is £3,700 less than the diesel estate and that's serious money for cars in this price range.