If you’re looking for a petrol car, the standard offerings begin with the 350, which is a turbocharged and mildly-hybridised, 295bhp, four-cylinder 2.0-litre. We're yet to try this engine, though. But we have tried the turbocharged 3.0-litre straight-six engine in the 450 4Matic and, with a whopping 362bhp to call upon, it's fast; as in 0-62mph in just 4.8sec fast. Which is not bad considering this technically isn't the quick one; that's the AMG 53 4Matic, which we'll come to in a moment.
The 450 also uses clever mild hybrid technology, deploying small bursts of electrical power to get you off the line and up to speed quicker; it’s a boon, proving really positive when, for example, you’re pulling away from traffic lights or overtaking on the motorway.
The AMG 53 also uses the same 3.0-litre straight-six engine with all that clever hybrid tech, too, but the wick's been turned up to 429bhp. That sees the 0-62mph time decrease to 4.5sec and supplies even more overtaking urgency but, to be honest, because the 450 is so strong and costs over £15k less, we think that's the pick of the petrols.
Also, unlike other AMG products, the 53 doesn't really differentiate itself enough to justify that price hike. Like the 450 it sounds smooth and pleasant, but rather muted for a sportier offering; unless you switch it to its sportiest mode, when it just sounds digitally enhanced and rather contrived.
As for diesels, the range starts with the 350d 4Matic, boasting a 2.9-litre straight-six engine and 282bhp. It’s very quiet at a cruise, but has as much pulling power as anyone would ever need – and then some. It’s not quite the full-fat, 335bhp 400d 4Matic, but it’s a tidy sum cheaper and ever so slightly more frugal. All things considered, it’s our pick of the range.
The 350d is great, then, but the 400d is a belter for those willing to splash the cash. It's super-smooth most of the time – certainly more so than the equivalent diesels in the Audi A7 Sportback and BMW 6 Series GT – and there’s effortless pace available with just a tickle of the accelerator; gun it, and it takes on a slightly harder-edged growl while the pace turns ballistic.
The standard nine-speed automatic gearbox used on all the above is decidedly slick and responsive, but not everything else is quite so cultured. While the CLS is whisper-quiet and more hushed than its rivals on the motorway when it comes to wind noise, road and suspension noise (with the standard passive suspension) are noticeably worse.
On standard passive suspension, the ride in town is rather lumpy over ruts and ridges compared with a 6 Series GT – even on the smallest (19in) wheels available. It does settle down nicely on the motorway, though, but not to the same extent as a smooth-riding A7 Sportback fitted with optional air suspension.
You can fit adaptive air suspension to the CLS (standard on the AMG 53 Edition 1 trim), as well, but unfortunately it is a let down. In the softest Comfort mode, it soothes out bumps around town up to a point, but strike a large, sharp-edged obstacle with any pace and the suspension will produce a forceful thwack so worryingly loud that you might think you've damaged something. Again, it gets better at speed, feeling quite wafty on the motorway; that suppleness disappears if you press the Sport button with a little more fidget over rippled roads, but the positive is better control over crests and dips.
What is commendable is the way the CLS handles. Okay, it’s not as pin-sharp or finessed as the more expensive Porsche Panamera, which would be the keen driver's choice here, but it feels similarly sure-footed to an A7 Sportback along a twisting back road, and much nimbler and neater than the taller, more wallowy 6 Series GT. The steering is precise and predictable, the brakes smooth and dependable and, with the four-wheel drive of the various 4Matic models, it’s tractable, even in slippery conditions.