Mercedes GLB review

When it comes to SUVs, we’re spoilt for choice. There are small ones, big ones, rugged ones, fast ones, hybrids and even fully electric ones. But with such a great variety, it’s surprising that there are so few seven-seat SUVs with a premium badge – at least ones that aren’t the size of an aircraft carrier. That's where the Mercedes GLB steps in.

The ‘B’ in its name might lead you to think it’s smaller than the GLC, which it is, but by only a couple of centimetres. And the GLB is available with an extra row of seats, just like its chief rival in the large SUV class, the Land Rover Discovery Sport.

We say 'chief rival', because you could also be looking at the similarly priced Audi Q5 and BMW X3, but those are five-seaters only. If you can live without the premium badge, but absolutely must have seven seats, don't forget that there are cheaper and excellent alternatives, including the Peugeot 5008.

Back to the Mercedes GLB, though, which, underneath, is closely related to the B-Class MPV. It comes with the option of four engines – two diesels and two petrols – including the AMG-fettled GLB 35 (that's the fast one, for those of you after a bit more oomph). All come with an automatic gearbox as standard, and there's a choice of two or four-wheel drive depending on which engine you go for. 

So, should the Mercedes GLB be at the top of your wish list, and how does it stack up against its key rivals? Read on for the answers to those questions and more, as we take you on a deep dive into the GLB model range.

By the way, if you like the look of the GLB but want something that runs on electricity, check out our Mercedes EQB review – the EQB is a seven-seat electric SUV that shares many parts with this car.

And remember, if you do decide it’s the car for you, make sure you check out our New Car Buying service, because you could potentially save thousands on a new GLB, without having to go through the hassle of haggling.

The entry-level 1.3-litre petrol (badged GLB 200) has a seemingly healthy 161bhp and is fine for just pootling around town or when you’re by yourself. However, because most of its power arrives high up in the rev range, you’ll find it struggles on faster roads, and particularly when seven people are on board. It doesn’t help that its standard seven-speed automatic gearbox is slow to react when you ask for a burst of acceleration.  

The gutsier diesels have a more responsive eight-speed auto 'box and are altogether better suited to the GLB. We prefer the 187bhp 220d over the 148bhp 200d (both are 2.0-litres), because its muscularity is a perfect fit for the GLB’s bus-like accommodation. It can get from 0-62mph in 7.6sec, which is quite a bit quicker than a Land Rover Discovery Sport D200 can and is on a par with the BMW X3 20d. It pulls strongly between 1500rpm and 4000rpm and can tow a caravan along without much difficulty, too. 

The most powerful engine is the 302bhp 2.0-litre turbocharged petrol in the AMG 35. That can hit 0-62mph in just 5.2sec, aided by its standard-fit launch control system and four-wheel drive.

This is one of the GLB’s weakest areas. Most versions jostle you around over uneven road surfaces, and tend to really thump over potholes, whereas the rival Discovery Sport is very comfortable, aside from a bit of float over undulations.

The AMG 35 comes with its own adaptive suspension, which you can soften or firm up on demand. It's wafty enough in Comfort mode, but really firms up if you switch to Sport.

If you’re searching for outright fun behind the wheel, an Alfa Romeo Stelvio or BMW X3 would serve you better.

Still, the GLB has enough composure that it's not alarming to drive spiritedly, and the steering, while slow, is accurate and weights up with enough conviction to inspire confidence. There's more outright grip than a Discovery Sport generates, too. 

The lowered and stiffened AMG 35 disguises its height better than the standard GLB, but it's not as agile or as hunkered down as the best sporty SUVs.

All of the engines are hushed when you're cruising along the motorway, but the 200 petrol is coarse when you work it hard, which you often need to do. The diesels aren't as screechy at high revs, but they do rumble away in most situations; not in an irritating way, but more so than a Q5 40 TDI.

The AMG 35 is deliberately noisier, although it isn't particularly entertaining to listen to, in part because some of what you hear on the inside is augmented via the speakers and sounds fake.

There's quite a bit of suspension noise in the GLB, and its door mirrors whip up wind noise at high speeds. Road noise on coarse surfaces is also fairly pronounced so, overall, if you like a bit of peace and quiet, you'll enjoy a Q5, X3 or Discovery Sport rather more.

You’ll have no complaints about the amount of reach and height adjustment that you get with the steering wheel. However, you don’t get adjustable lumbar support unless you go for the top-level AMG Line Premium Plus trim, which brings many extras on top, including full electric seat adjustment with a memory function.

The GLB’s driver’s seat is also narrow enough to make you question whether you’ll still fit if you eat dessert, plus some people will find the non-adjustable lumbar overly firm, and you sit comparatively low in the car, so that you almost feel like you're in a hatchback rather than an SUV. The Land Rover Discovery Sport, by contrast, offers a wide, comfortable seat and the sort of view usually reserved for HGV drivers.

All GLBs come with digital instruments instead of conventional dials, and you can arrange them in a number of modes and styles. As standard, it's a 7.0in screen but, if you step up to AMG Line Premium, it grows to 10.25in. The rest of the dashboard layout works well, with a row of simple buttons to manage the climate control.

The GLB's big, square windows provide a great view out of the front and to the sides, but look back over your shoulders and there are blindspots behind each rear pillar. You get a rear-view camera as standard to help mitigate those, but front and rear parking sensors are standard only once you get to AMG Line Premium trim.

Every GLB gets LED lights all round, including the headlights, and top-spec AMG Line Premium Plus models have adaptive LED headlights, which you can leave on main beam, because they automatically shape their light to avoid dazzling other road users.

As standard, you get a 7.0in infotainment screen with crisp graphics and responsive software. Built-in sat nav, Bluetooth and a DAB radio are all included, while upgrading to AMG Line Premium expands the screen’s size to 10.25in, and adds wireless phone charging as well as Apple CarPlay and Android Auto smartphone mirroring.

Whatever the screen size, it can be operated either as a touchscreen or via a touchpad controller (similar to a laptop's) between the front seats. The latter method is less distracting when you're driving, and gives the GLB an advantage over pure touchscreen systems like the one in the Discovery Sport.

There are also two tiny touchpads on the steering wheel that you can use to control the system, or you can rely on the natural speech voice control for many things, which you wake up by calling out "Hey Mercedes". Overall, the GLB's infotainment system is only surpassed by the BMW X3's.

Even without the atmosphere created by the ambient interior lighting in AMG Line Premium models, the GLB still strikes a classy pose. The twin digital displays offer a clean and modern look, and the most prominent areas, such as the top of the doors and dashboard, are upholstered in soft plastic or artificial leather.

Just bear in mind that some of the materials used lower down are considerably less appealing than those in your eyeline, and the air-con panel flexes when you use it. Interior quality is roughly on par with the Discovery Sport, then, but not as good as in the Audi Q5 or BMW X3.

The boxy shape of the GLB means there's lots of front space. Even the optional sunroof doesn’t do much to dent head room, and leg room is copious, even for tall drivers and front passengers. 

There's also plenty of space to store odds and ends. Push a button at the base of the centre armrest and it reveals a deep cubby; in front of the infotainment touchpad, there’s another lidded cubby as well as two cupholders and a dedicated area for your smartphone. Even the door pockets are big.

Six-footers will find they have plenty of leg room in the GLB’s second row. However, the Land Rover Discovery Sport offers more shoulder room for three people sitting side by side, and head room is also worse in the GLB, because Mercedes’ has mounted its second-row seats much higher than those in front.

The upside of this tiered approach is that kids get a better view forward and out the side windows, so might be less prone to car sickness. And like the Discovery Sport, most GLBs have two further seats that fold up from the boot floor, which is a benefit that the Audi Q5 and BMW X3 cannot match.

As is the case with the Discovery Sport, you have to squeeze through a narrow gap to get to the GLB’s third row. And once there, you’re left in no doubt that you’re in the cheap seats, because your knees are pushed up high and there’s a lot less head room than there is in the first two rows. However, smaller adults and teenagers will fit more comfortably than they do in the Discovery Sport because, unlike its rival, the GLB has room for your feet beneath the seats in front.

Every GLB has second row seats that can be slid back and forth to suit your needs. However, while the Discovery Sport's three second-row seats each slide independently of one another, the GLB's only move in a 60/40 split.

This hampers versatility a little, but the seatbacks can at least all be reclined independently. And the third row seats are easy to stow and erect.

Opening the tailgate reveals a pretty square cargo area with a no lip at the entrance, making it easy to load and unload bulky objects. With five seats in use, there's 500 litres of space up to the tonneau cover, which is enough for a couple of buggies or large suitcases, but not as much as an Audi Q5, BMW X3 or Land Rover Discovery Sport offer. If you have all seven seats in play, there’s space for a row of shopping bags, but that's about it. 

However, something that the GLB has that the Discovery Sport misses out on is a dedicated slot for the parcel shelf under the boot floor. That comes in handy when you suddenly have cause to deploy the third row of seats.

Looking at brochure prices, the GLB is competitively pitched against its premium seven-seat rival, the Land Rover Discovery Sport, as well as posh five-seat SUVs, such as the Audi Q5. If you aren't overly bothered about a premium badge, though, there are more affordable SUVs that can seat seven, such as the Peugeot 5008. 

An upside of the GLB’s posh badge is that it depreciates quite slowly (although not as slowly as the Discovery Sport). And this helps its PCP finance deals look quite tempting when compared with those of some non-premium alternatives (although again the Discovery Sport has the advantage).

Our preferred engine – the 220d – compares favourably with the Discovery Sport D200 for official fuel economy. And all the engines are RDE2 compliant, which means there's no 4% diesel benefit in kind tax surcharge to inflate company car tax.

Sport is the entry-level trim but it still has all the basics, including 18in alloy wheels, dual-zone climate control, man-made leather upholstery and heated front seats, plus the infotainment and visibility aids we've covered off already. AMG Line doesn't bring a lot more to the table, other than 19in alloy wheels, privacy glass and a more aggressive bodykit.

The bigger infotainment screens and the clever augmented sat nav we mentioned earlier all come with AMG Line Premium trim. That also gets you ambient lighting inside and keyless entry, which, altogether, make up for its additional cost. AMG Line Premium Plus is too pricey, though.

The GLB is too new to have featured in the 2020 What Car? Reliability Survey, but hopefully it’ll be more dependable than the Discovery Sport, which was one of the worst ranked cars. As a brand, Mercedes finished in 24th place out of 31; not overly encouraging but still ahead of Land Rover, which came last.

In terms of warranty, you get three years with unlimited mileage, which is pretty much standard for class. For added peace of mind you also get Mercedes roadside assistance when driving in the UK and Europe. If you want the best warranty a seven-seater SUV can offer, the Kia Sorento's lasts for seven years.

The GLB received five stars (out of five) for safety when appraised by Euro NCAP. It's tricky to compare its score with close rivals, though, because they were all tested a few years ago when the standards were more lenient. The GLB doesn't have any major issues, apart from a higher-than-average risk of adult chest injuries in a side impact. 

Useful safety aids, such as automatic emergency braking, lane-keeping assistance and traffic sign recognition, are standard on every GLB. If you want blind spot monitoring, though, you’ll only find it on the top trim level. Each third row seat has an Isofix point for the secure mounting of a child seat, as do the outer two seats on the second row. 

All GLBs come with a Thatcham-approved alarm and immobiliser, too.

For all the latest reviews, advice and new car deals, sign up to the What Car? newsletter here.