Mercedes SLK 55 AMG

The SLK 55 AMG brings something very special to the compact roadster class – a V8 engine, and a clever one, too. The cylinder deactivation technology works so smoothly that you barely notice it, and you’ll be thankful it’s there when you come to fill the tank. On the move, it sounds great and provides blistering pace, but the handling is a slight disappointment and not quite a match for the best in class.

It's one of those strange-but-true facts of life that as cars become faster, they get more fuel efficient, too. Mercedes’ new SLK 55 AMG is a prime example  – it has 60bhp more power than the model it replaces, and economy is up by 30 per cent. But does it drive as well as its predecessor?

Underneath the bonnet is a 5.5-litre V8 which produces 416bhp, but it comes with clever cylinder deactivation that shuts down half of the engine when you’re light on the throttle. That means it can not only accelerate from 0-62mph in 4.6 seconds, but it manages 33.6mpg.

Video: watch CarBuyer's video review of the Mercedes SLK

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The good news is that the fuel-saving tech works seamlessly up to 3,600rpm, and you still have 230Nm of the maximum 542Nm of torque available. There’s a slight change in the engine note, but a firm prod of the throttle soon returns the car to its full complement of cylinders and offers the familiar V8 burble we’ve come to expect.

At full pelt, the AMG is devastatingly fast in a straight line. Floor the throttle, and the seven-speed gearbox shifts down a couple of gears before you’re rocketed forwards with unrelenting pace to a limited top speed of 155mph.

The AMG, unsurprisingly, has stiffer suspension and sharper steering than other SLKs, as well as a braking system that helps the car tuck into bends by gently applying pressure to the inside wheels when you’re cornering hard.

The result is the sharpest-handling SLK yet, but the slightly lifeless steering can’t compete with the driving thrills offered by a Porsche Boxster.

The SLK can also be fitted with a handling package that stiffens the suspension even further, as well as adding a rear differential lock and composite brakes. We found that whichever set-up you choose, the low-speed ride isn’t great, but it’s no worse than other performance cars in this class.

The SLK AMG is not quite as pure as a Porsche Boxster, but it’s fun to drive. It flows sweetly between corners and the engine is extremely flexible.

Naturally, the bodywork and interior have been changed to ensure you know it’s an AMG, but the style and elegance of the original SLK 55 have not been lost along the way.