The lower-powered version of the four-cylinder 2.1-litre diesel engine (badged 220 d) is fast enough to satisfy the desires of most SUV buyers. The 250 d model is noticeably stronger at low and mid revs, however, which allows the standard nine-speed automatic gearbox to keep the engine revs lower and whisk you up to speed in a more relaxed fashion. It’s worth the relatively small premium.
The 3.0-litre V6 diesel gets the same nine-speed gearbox, and they works well together. The V6’s smooth power delivery helps make it the most luxurious GLC to drive, although it’s capable of keeping up with hot hatches should you need it to.
The top of the range GLC 43 AMG (before a V8 GLC 63 joins the range later) is powered a 3.0-litre twin-turbocharged V6 petrol engine, which drives all four wheels through a nine-speed automatic gearbox. It’s incredibly quick, matching the Porsche Macan and Jaguar F-Pace S for straight line pace. Just be aware that this impressive performance comes at the price of fuel economy.
Mercedes-Benz GLC ride comfort
Go for SE or Sport trim and you’ll get the softest of the two conventional suspension set-ups available. Common sense would suggest this is the better option if you want a comfortable ride, but in reality there's too much side-to-side movement along any road that isn't perfectly smooth, so your head is tossed from left to right continually. Potholes also flummox the suspension too easily, particularly when cornering forces are involved, causing the GLC to skip and shudder nervously.
The firmer sport suspension – fitted to AMG Line models – is a little less forgiving over bigger obstacles, such as speed bumps, but overall it's actually the more comfortable set-up. It brings a more controlled ride with less pitch and wallow, and more effective damping over potholes and broken surfaces. That’s true even if you choose to upgrade from the standard 19in wheels to the optional 20s.
However, it’s the air suspension that comes available as an option on all three trim levels that’s the most impressive on UK roads. We tested it on the top-of-the-range GLC 43 AMG, and despite that car coming equipped with large 19in wheels, the suspension did an impressive job of smoothing out imperfections.
Mercedes-Benz GLC handling
The Mercedes GLC handles well enough for a large SUV. Even SE and Sport versions stay relatively upright through corners and grip the road well , while the firmer suspension and lower-profile tyres of AMG Line models results in a more precise front end that responds more promptly to steering inputs.
If you want a more thrilling driving experience, however, the GLC 43 AMG is your best bet. With Airmatic suspension and a rear-biased four-wheel drive system, the 43 is a surprisingly competent through twisty bits by SUV standards.
Whichever version you choose, however, it’s a real pity the GLC’s steering isn’t better; it weights up in a very unnatural way when you turn in to corners and, because the steering is variable (it gets progressively quicker as you apply lock), it's hard to corner precisely at faster speeds.
Mercedes-Benz GLC refinement
The GLC’s four-cylinder diesel engines (in the 220 d and 250 d) are quite gruff. There’s a chug at tickover and an uncouth rumble as the revs rise, but we could level the same criticisms at the rival BMW X3. In fact, the only close rival with considerably better engine refinement is the Audi Q5.
You hear less of the engine in the more powerful 250 d simply because it doesn’t need to work as hard to achieve the same turn of pace. Meanwhile, the standard nine-speed automatic gearbox shifts smoothly most of the time, even if it’s a little jerky at very low speeds. The V6 diesel is in a different league - it’s never noisy and always smooth, no matter how hard you push it.
The stop-start system, which cuts the engine when you come to a halt to save fuel, isn’t the smoothest of its type because when it fires the engine back into life the whole car shudders. There's a bit of road noise if you choose big wheels, which makes motorway journeys less peaceful than they might be.
One of only two engines to choose from, this 168bhp 2.1-litre diesel is paired with a nine-speed automatic gearbox. It pulls well enough and can ultimately whisk the GLC from 0-60mph in a respectable 8.3 seconds, although the gutsier 250 d can accelerate up to speed quickly in a more relaxed fashion, so is worth the small premium.
Our pick 250 d
Our preferred engine is essentially the same 2.1-litre diesel found in the entry-level 220 d. However, it’s been tuned to produce an extra 33bhp and considerably more low-end shove, which makes faster driving more effortless. A nine-speed automatic gearbox comes as standard.
A powerful yet smooth diesel engine that helps the GLC feel its most luxurious. Expensive, though, and company car drivers will be better off with the 220 d.
The top-of-the-range GLC 43 4Matic receives a 3.0-litre twin-turbo V6 petrol engine, a nine-speed automatic transmission and a rear-biased all-wheel drive system. Mercedes claim that a sub five-second 0-62mph time should be achievable and, given the space, the GLC 43 should rocket up to an electronically limited 155mph top speed. With plenty of low down shove, it’s a flexible engine, and feels well suited to the mid-sized SUV.