IT'S no secret that cars depreciate faster than unwanted Christmas presents and, as we all know, some lose pounds faster than others.

So the only way to attempt to defy this trend, unfortunately, is to invest a fair amount of cash in four wheels in the first place.

The old marketing philosophy that you have to spend money in order to make money is just as valid in the used car world as it is when attempting to flog the latest widget to clueless consumers.

One sector that always bucks the current trend for gently sliding values is the premium roadster market, and one car with a better than average track record is the Mercedes SLK.

The Merc with the clever folding metal roof has been around since 1996 but, like the previous generation SL, the first generation model has aged well and still looks good even when compared to BMW's rakish Z4.

However, the difference between other premium car maker's products and the one sporting a three-pointed badge is that the SLK was never developed as an out-an-out thrill machine. You buy the SLK primarily to be seen in, not to tear up the countryside in.

Boasting a roof that lifts, folds and contorts itself into the boot at the press of a button, shy and retiring types need not apply. Perform this equivalent of automotive ballet outside your local pub and you'll attract envious and interested gazes in equal measure.

When considering an SLK, it's the initial outlay that will hurt the most - no matter how much cash you have squirreled away for a rainy day, the SLK is not a cheap car.

If there is any consolation, it's the fact that the cars generally behave themselves, as unreliability issues are few and far between.

What you consider to be expensive will differ from the next person, but if you want the SLK experience without breaking the bank, your best bet is an early pampered car with plenty of history.

At launch, only one variant was offered, the 230K, which should make shopping that bit easier.

The only thing to remember is to pick a car with an auto gearbox and, preferably, leather upholstery.

Many traders and private buyers take a dim view of Mercs with clutch pedals, and a manual box can shave valuable pounds off a car's sticker price.

Leather trim, while not essential, is looked on favourably by both the trade and private punters - something to bear in mind if you choose to part with your SLK at a later date.

It goes without saying that any car you buy should be bursting with creature comforts. The beauty of fully loaded models is that none of the added extras should cost you any extra cash, as the only things to depreciate on a Merc are the likes of the powered seats, air-con and alloy wheels. Oh, the irony.

There's no real need to state the obvious when dealing with a potential purchase costing this much cash, but you'd be mad not to get the car's history professionally checked and run its paperwork under a microscope.

Everything must work first time and there shouldn't be any strange noises from under the bonnet or from the roof mechanism.

Dents, scrapes and a less-than-perfect interior are the classic signs of an abused town runabout, so walk away.

l Verdict: Suave, sophisticated, but pricey.

WHAT TO PAY...

1996N/P: £10,580.

1997 P/R: £11,320.

1998 R/S: £12,400.

1999 T/V: £14,110.

2000 W: £15,625.

2000 X: £16,305.

REVISED MODEL...

2000 W: £15,935.

2000 X: £16,615.

2001 X/Y: £17,665.

2001 51: £18,755.

2002 02: £20,180.

2002 52: £21,065.

2003 03: £22,735.

2003 53: £23,375.

2004 04: £24,185.

All values relate to showroom prices for cars in A1 condition.