Absolutely fine, if not the most scintillating driving machine in its segment. With 250d badging, the Mercedes uses the venerable 2,143cc twin-turbocharged four-cylinder diesel engine, which has already been superseded in the E-Class
by the 192bhp, 1,950cc turbodiesel, but the spread of the new engine to the rest of the Mercedes range hasn’t started in earnest yet.
Having said that, in a car where you can open the roof to hear its exertions more clearly, this is one of the quietest installations of the 2.1 we’ve encountered. This is both a blessing and a curse for the SLC, because it makes it a highly refined car to cruise in, but when driven in a more spirited fashion there’s little audible reward for the driver. Some four-cylinder turbodiesels, mostly from the Volkswagen Group, can make a moderately interesting noise, yet the Mercedes does nothing but emit a discreet, rumbling note under duress. It’s not bad, but neither is it alluring.
There’s nothing wrong with its performance, however, as a massive 369lb ft accessible from 1,600- to 1,800rpm has little trouble punting 1,605kg of convertible about. It maybe doesn’t feel quite as quick as a 6.6-second 0-62mph time suggests, but the SLC 250d can be hustled along at a decent pace and there’s little turbo lag to overcome, either. One note of caution to sound here – the SLC’s official 70.6mpg economy figure seems wildly optimistic, given we saw around 35mpg during a moderately quick drive.