Mercedes SL500

Let's play spot the difference. After all, there's no denying Mercedes' facelifted SL does at first glance look just like the old one. On sale in the UK now, it has redesigned front and rear lights, plus a revised range of wheels. Less obviously, there are new chrome surrounds on the foglights, and larger air intakes on the flanks.

Inside, the changes are even harder to see, particularly if the doors are closed - covering up the new kick plates on the sills. We managed to identify a couple of strips of new trim, but missed the additional double stitching on the instrument binnacle completely!

So you can see why it would be so easy to feel cynical about the 'new' SL and its £1,780 price hike. But look more closely at the car's technical specification, and you'll see that there are some significant design modifications - beginning with the smooth-operating metal hard-top.

New hydraulic pistons and revised software mean the roof now stows in only 16 seconds - four seconds quicker. A freshly designed boot gives 22 litres of extra storage space, while there's an optional button available that closes its lid automatically.

With the engine running, it's clear the new 388bhp V8 instantly offers greater refinement. Crucially, the SL500 now uses a 5.5-litre, rather than 5.0-litre, engine to deliver its impressive power, and the effect on its performance is immediately apparent.

Throttle response is smoother and sharper, and power delivery is much more even, thanks to the improved 580Nm torque output from low revs. Straight-line speed is also helped by the seven-ratio automatic gearbox. We have criticised its action in the past, but here it works like a dream, shifting ratios virtually unnoticed.

The top speed is still electronically limited to 155mph, but the 0-60mph sprint time has dropped from 6.1 seconds to just 5.4 seconds, while fuel economy remains at 23.2mpg.

The SL also rides more smoothly than before, and the chassis somehow feels more stable. Mercedes says no physical changes have been made to the set-up, but software alterations to the air-sprung system have delivered small improvements.

On an open road, the car is a real joy to drive, while all the modifications have given the SL's character and quality a boost. If you can stomach the huge £75,880 price, it makes the rise of just under £2,000 from the previous model look decent value.