The six-cylinder versions of the second-generation Mercedes CLS are so impressive on so many levels that you might be inclined to overlook the entry-level four-cylinder CLS250 CDI. But you’d be making a big mistake. Powered by a twin-turbo 2.1-litre diesel engine with 201bhp and a thumping 369lb ft of torque, the CLS250 CDI not only has more than adequate performance but also gives usefully lower fuel consumption and CO2 emissions than any of its six-pot siblings.
The CLS350 CDI gets an upgraded 3.0-litre V6 common rail diesel providing a good balance between performance, economy and refinement. Mercedes-Benz claims 0-62mph in 6.2sec – an improvement of 0.8sec over the earlier CLS350 CDI. It’s through the gears, though, that the gains are more noticeable. The real strength of the petrol V6 in the 350 BlueEfficiency is not its outright performance but its clean, flexible power delivery and the ability to be silent and serene, or rasping and urgent according to demand.
The CLS 500 petrol uses a brand new 4.7-litre twin-turbo V8, which produces 20bhp more than the old naturally aspirated 5.5, 52 additional pounds of torque, and is also 25 per cent more fuel efficient.
This is a five metre, near two-tonne four seater, capable of better than 30mpg on the run, and yet that also has 402bhp and can hit 62mph in under five and a half seconds. The CLS63 AMG will take no longer than 4.4sec to reach 62mph according to AMG. We only managed 5.2sec but, given we spent half of that reaching the first 30mph, faintly glacial by the standards of these cars, we don’t doubt the 4.3sec claim one iota. Despite the tardy start our test CLS posted a sub 10 second time to 100mph. Make no mistake, the CLS63 AMG is comfortably in the top division of saloon performance.