Used sports cars tested: Porsche Boxster vs Mercedes SLK

What will they cost?

When these two cars were new, the Mercedes-Benz cost almost £10,000 more than the Porsche – a not-insignificant figure, especially when you consider that today you can buy them for almost the same price. And in fact, it’s the SLK that looks fractionally the cheaper car – especially when you consider that most Boxsters come with a heap of extra equipment, which pushes the price up even further.

What’s more – and somewhat incredibly – the SLK is the cheaper car to fuel, too, according to the official figures. Despite being equipped with an engine that’s a whole two litres larger than the Porsche’s (not to mention one with two extra cylinders), the SLK manages 33.6mpg on average to the Boxster’s 32.1mpg.

That distinction also means that the SLK has lower emissions, and as a result, it slips into a lower tax band, costing £275 a year to tax, compared with the Porsche’s £290. What’s more, the SLK is the cheaper car to service, too.

But what about deprecation? Well, it’s true that the Mercedes loses a whole heap of its value when it’s new, so if you’re buying examples that are a couple of years old, you might well find any cost saving you get with the Mercedes is wiped out by the cash you lose.

However, after a few years – and certainly by the age of our two test cars – the SLK’s depreciation curve flattens out, and it tends to lose its value no more rapidly than the Porsche.

In other words, if money is a factor, the Mercedes has a very distinct edge over the Porsche, both in terms of how much it’ll cost you to buy and how much you’ll spend owning and running it. That said, the difference isn’t vast; while it’s true that the Porsche is the more expensive car, it isn’t exactly financially ruinous in comparison.