Mercedes GLA vs GLB
Does the more practical GLB make the GLA obsolete?
Both these Mercedes SUVs belong in the subcompact size class, but the GLB is almost 10 inches longer. The GLB can therefore accommodate up to 7 passengers and boasts more cargo space. However, the extra weight comes at the cost of performance.
2021 Mercedes-Benz GLA-Class SUV GLA 250
- Body Type
- MPG (City/Hwy)
- 25 / 34
2021 Mercedes-Benz GLB-Class GLB 250
- Body Type
- 3,638 lbs
- MPG (City/Hwy)
- 23 / 31
Note: Images shown may not represent trims
The SUV equivalent of the A-Class, the GLA has been the entry-level subcompact SUV in Mercedes’ lineup. However, with more and more consumers buying SUVs, Mercedes added the GLB model to their lineup in 2019.
Belonging in the same subcompact SUV crossover class as the GLA, the GLB is positioned alarmingly close to it, but as we’ll find out in this comparison, there are enough differences between the two to make sure they’re not fighting for the same market.
Being the most affordable SUV in the company’s lineup, the GLA 250 starts at $36,230 excluding destination charges. Mercedes don’t offer a selection of trims to choose from, and the only other model is the 4Matic all-wheel drive version that costs an extra $2,000.
The GLB 250 costs a little more, starting at $38,050 excluding destination charges. Once again you get the option of going AWD for an extra $2,000.
Those seeking the ultimate driving experience will want to consider the more expensive AMG GLA 35 ($47,550) and AMG GLB 35 ($49,500) SUVs, which both have tuned 302-horsepower engines among other improvements. Mercedes-AMG also offers the even quicker AMG GLA 45 for $54,500, but no equivalent GLB is available.
Both the Mercedes GLA and GLB are classed as subcompact SUVs, meaning they’re relatively small compared to some of the other monsters running on roads. That being said, they look remarkably different.
The Mercedes GLA is more representative of a modern day subcompact SUV, with a sloping roofline and lean profile. The GLB, on the other hand, has a boxy appearance which is charming in its own way, and no doubt necessary to accommodate an extra two passengers.
The exterior styling differences aren’t limited to shape, either. The GLB gets its own headlamps and tail lights which look completely different from those on the GLA. We’ll leave it to you to decide which looks better.
Moving inside, the Mercedes GLA and GLB feature the exact same dashboard and center console.
As one would expect from Mercedes, the interior on both crossovers can be had with leather upholstery and a natural wood grain trim. You also get the option to add 64-color ambient lighting LEDs and illuminated air vents which adds a splash of pizazz during night drives.
These modern interiors deviate from other SUVs on the market with a single panel MBUX interface that contains the driver’s digital instrument cluster on the left and the touchscreen infotainment display on the right.
As standard both displays are rather small at 7-inches, so most buyers will want to option the Premium Package which upgrades them to larger 10.25-inch displays.
Of course, the two SUVs are different when we move to the back of the car, which brings us to the next section...
Passenger Space and Cargo Volume
This is where the Mercedes GLA and GLB fundamentally differ. The GLA is a standard subcompact crossover SUV which accommodates up to 5 people at most. But the GLB can accommodate up to 7 thanks to two extra folding seats at the back – an impressive feat given the relatively small space Mercedes had to work with. (Note that the 7-seat configuration is an optional extra that will cost an extra $850 on top of the price of a 5-seat GLB.)
Now if you thought the GLB would be a squeeze compared to the GLA, worry not, because the GLB is around 10 inches longer on the outside meaning they haven’t taken away anything from passengers in the front and back.
As for cargo space, the extra length of the GLB means it has a whopping 62 cubic feet of cargo volume when back seats are folded. The GLA manages 50.5 cubic feet, which is good, but not great.
Both the Mercedes GLA and GLB house the same 2.0-liter Inline-4 turbo engine under the hood. This produces 221 horsepower and 258-lb of torque, and gets both crossover SUVs from 0-60 mph in less than 7 seconds. This engine is paired with a snappy 8-speed automatic transmission.
However, the GLA is the faster car, because it weighs less. The difference is definitely noticeable, as the engine was designed with the GLA in mind, meaning the GLB can feel a little underwhelming performance-wise. The lower ground clearance of the GLA also makes it more confident taking on corners at speed, though the GLB’s higher ride height is an advantage in itself.
As with most crossover SUVs, neither the GLA or GLB is particularly well-suited to off-roading. But paying extra for the AWD 4Matic version of either car will definitely make them far more capable on harsh terrain.
Once again, the GLA’s lighter body becomes advantageous, this time in the way of delivering superior fuel efficiency.
The Mercedes GLA SUV manages 25 mpg in the city and 34 mpg on the highway according to EPA estimates. Compare that with the Mercedes GLB, which manages a slightly lower 23 mpg in the city and 31 mpg on the highway.
Both the GLA and GLB SUVs share the exact same impressive list of features as standard, including the Mercedes-Benz User Experience (MBUX), voice control and the ‘Hey Mercedes’ activation phrase.
Besides the touchscreen infotainment, you also get a touch pad on the center console and touch controls on the steering wheel. You can even option a color head-up display. Everything about the technology inside these cars is modern.
For your cell phone, there’s four USB-C ports and Bluetooth connectivity and optional wireless charging. Apple CarPlay and Android Auto connectivity is a given, of course.
The two SUVs feature the same standard and optional safety features. As standard you’ll get active brake assist, adaptive braking and emergency braking with pedestrian detection.
Buyers can purchase the ‘Driver Assistance Package’ which adds a host of assists, including adaptive cruise control, lane keeping assist, blind spot assist and more.
Neither SUV crossover has been safety rated by the NHTSA or IIHS so far. They did however score the highest possible 5-star safety rating in European NCAP testing.
The GLA’s key rivals are the BMW X1/X2, Audi Q3 and Lexus UX. The GLB is pretty much unchallenged, you just don’t find other subcompact SUVs with 7 seats.
Both the Mercedes GLA and GLB subcompact SUVs share a lot in common, but the markets they target are clearly distinct.
The Mercedes GLA is your standard 5-seater subcompact SUV. It’s smaller overall and weighs less, meaning it drives better and has a better fuel economy. It also costs slightly less.
The Mercedes GLB trades performance for practicality, offering more room for cargo and the ability to seat 7. It also gets its own unique look that is more representative of a typical SUV.
We’d recommend the GLB (with the third-row seating add-on) to families with children – you can count on the need for additional seats coming up at some point. But for everyone else, the GLA just makes more sense.
Related: Mercedes GLA vs GLC
Full Comparison Table
|2021 Mercedes-Benz GLA-Class SUV GLA 250||2021 Mercedes-Benz GLB-Class GLB 250|
|Engine||2.0-liter Turbo Inline-4 Gas||2.0-liter Turbo Inline-4 Gas|
|Horsepower||221 hp @ 5500 rpm||221 hp @ 5500 rpm|
|Torque||258 lb-ft @ 1620 rpm||258 lb-ft @ 1800 rpm|
|Transmission||8-Speed Automatic||8-Speed Automatic|
|Drivetrain||Front-Wheel Drive||Front-Wheel Drive|
|Front Wheel Size||18" x 7.5"||18" x 7.5"|
|Rear Wheel Size||18" x 7.5"||18" x 7.5"|
|Turning Diameter (ft.)||-||38.4|
|MPG - Combined||28||26|
|MPG - City||25||23|
|MPG - Hwy||34||31|
|Gas Tank Size (gallons)||13.5||15.9|
|Cruising Range - City (miles)||337.5||365.7|
|Cruising Range - Hwy (miles)||459||492.9|
|CO2 Emissions, 15K mi/year (tons)||6.4||6.9|
|Max Width (in.)||72.2||72.2|
|Front Width (in.)||63.2||63.2|
|Rear Width (in.)||63.2||63.2|
|Legroom - front (in.)||41.1||41.4|
|Headroom - front (in.)||40.8||40.7|
|Hip Room - front (in.)||57.3||-|
|Shoulder Room - front (in.)||55.9||55.9|
|Legroom - rear (in.)||38.4||38.1|
|Headroom - rear (in.)||38.1||39.3|
|Hip Room - rear (in.)||57.3||-|
|Shoulder Room - rear (in.)||54.8||54.9|
|Hard Disk Drive||Not Available||Not Available|
|MP 3 Player||Standard||Standard|
|Premium Sound System||Optional||Optional|
|Wifi Hotspot||Not Available||Not Available|
|Aux Audio In||Standard||Standard|
|Entertainment System||Not Available||Not Available|
|Head Up Display||Optional||Optional|
|Steering Wheel Audio Controls||Standard||Standard|
|Power Mirror S||Standard||Standard|
|Adaptive Cruise Control||Optional||Optional|
|Automatic Parking||Not Available||Optional|
|Cooled Front Seat S||Optional||Optional|
|Cooled Rear Seat S||Not Available||Not Available|
|Hands Free Liftgate||Optional||Not Available|
|Heated Front Seat S||Optional||Optional|
|Heated Rear Seat S||Not Available||Not Available|
|Heated Steering Wheel||Optional||Optional|
|Multi Zone A C||Standard||Standard|
|Power Driver Seat||Standard||Standard|
|Power Passenger Seat||Standard||Standard|
|Remote Engine Start||Standard||Standard|
|Remote Trunk Release||Standard||Standard|
|Universal Garage Door Opener||Optional||Optional|
|Seat Massage||Not Available||Optional|
|Rear A C||Not Available||Not Available|
|Navigation From Telematics||Not Available||Not Available|
|Leather Steering Wheel||Standard||Standard|
|Premium Synthetic Seats||Standard||Standard|
|Woodgrain Interior Trim||Not Available||Not Available|
|Back Up Camera||Standard||Standard|
|Cross Traffic Alert||Not Available||Not Available|
|Rear Parking Aid||Optional||Not Available|
|Blind Spot Monitor||Standard||Standard|
|Lane Departure Warning||Not Available||Optional|
|Lane Keeping Assist||Not Available||Optional|
|Night Vision||Not Available||Not Available|
|Tire Pressure Monitor||Standard||Standard|
|Driver Air Bag||Standard||Standard|
|Front Head Air Bag||Standard||Standard|
|Front Side Air Bag||Standard||Standard|
|Knee Air Bag||Standard||Standard|
|Passenger Air Bag||Standard||Standard|
|Rear Head Air Bag||Standard||Standard|
|Rear Side Air Bag||Optional||Optional|
|Seatbelt Air Bag||Not Available||Not Available|
|Basic||4 Years / 50,000 Miles||4 Years / 50,000 Miles|
|Corrosion||4 Years / 50,000 Miles||4 Years / 50,000 Miles|
|Drivetrain||4 Years / 50,000 Miles||4 Years / 50,000 Miles|
|Roadside Assistance||4 Years / 50,000 Miles||4 Years / 50,000 Miles|