BOARDROOM expresses that were originally very expensive are not for the faint hearted secondhand. They are thirsty, expensive to insure and costly to fix.

However, they usually have an excellent reputation for reliability and the Mercedes S-Class is not least among them.

Few cars are more superbly comfortable and capable than the S-Class, and this has placed it at the top of the luxury car list for years.

The four-door saloon is the epitome of sophistication. It has unrivalled refinement and an interior that insulates the occupants completely from the outside world.

If this is your kind of car, you'll get marvellous comfort, excellent handling and surprisingly good roadholding.

Since 2006 there is a wide range of engines. Petrols go from a 3.0-litre with 227bhp to a twin turbo AMG 6.0-litre with an incredible 603 horsepower.

Diesels are all 3.0-litres with power from 227 to 254bhp.

All have an automatic gearbox, and high specification as standard. Even with the smaller engines, performance is more than enough for most people.

But never buy without full service history. You need to know it has all been done so that high mileage is not a problem.

The interior is beautifully styled and blends classic and modern elements to produce unashamed luxury.

All have leather, electric seats, climate, self-adjusting airmatic suspension, multifunction leather steering wheel, trip computer, electrically adjustable steering column, metallic paint, wood trim, rain sensitive wipers, sat nav and a CD stereo with an eight-inch colour display.

All are very safe and have loads of electronic wizardry to keep you on the straight and narrow.

Pay around £9,350 for an '08 08-reg S320 CDI (original price £55,000) or £17,000 for an '11 11-reg S350 BlueEFFICIENCY.