GLA vs GLB is the choice between the two smallest Mercedes SUVs. They share the same 221-hp turbo engine and cost within about $4,300 of each other, but the GLA is lower and sportier, while the taller, boxier GLB has far more cargo space and an optional third row.
This GLA vs GLB comparison uses Cars.com and CarGurus figures for the 2026 GLA 250 and 2025 GLB 250 to compare price, size, space, seats and fuel economy.
GLA vs GLB: quick answer
- Buy the GLA if you want the cheapest Mercedes SUV, the best fuel economy and an easy car to park.
- Buy the GLB if you need more cargo space, more headroom or occasional seven seats.
GLA vs GLB specs compared
| Spec | GLA 250 (2026) | GLB 250 (2025) |
|---|---|---|
| Starting price (MSRP) | $41,500 | $45,800 |
| With 4MATIC AWD | $43,500 | $47,800 |
| Engine | 2.0L turbo 4-cylinder, 221 hp | 2.0L turbo 4-cylinder, 221 hp |
| Torque | 258 lb-ft | 258 lb-ft |
| Fuel economy (city/hwy/combined) | 26/34/29 mpg | 25/33/28 mpg |
| Seats | 5 | 5, or 7 with the optional third row |
| Length | 173.6 in | 182.4 in |
| Height | 63.5 in | 65.3 in |
| Wheelbase | 107 in | 111 in |
| Cargo behind second row | 15 cu ft | 22 cu ft |
| Max cargo space | 51 cu ft | 62 cu ft |
Sources: Cars.com specifications (prices exclude destination); CarGurus 2026 GLA pricing.
GLA vs GLB price
The GLA is the cheapest way into a Mercedes SUV. Cars.com lists the 2026 GLA 250 from $41,500, or $43,500 with 4MATIC, against $45,800 and $47,800 for the GLB 250. CarGurus, which includes the $1,250 destination fee, lists the GLA 250 from $42,750.
If you want performance, the AMG GLA 35 costs $59,800 according to CarGurus, with 302 hp and a 0–60 mph time of 5.1 seconds. Canada’s Guide Auto reports that Mercedes has dropped the AMG version of the GLB for 2026.
GLA vs GLB size
The GLB is 8.8 inches longer, 1.8 inches taller and has a 4-inch longer wheelbase. That makes a bigger difference than it sounds: the GLB’s square body gives more headroom and a much larger cargo area, while the GLA is easier to park in the city.
GLA vs GLB cargo space
The GLB carries far more. Behind the second row it offers 22 cubic feet against 15 in the GLA, and with the rear seats folded it has 62 cubic feet against 51.
Seats and third row
The GLA is a five-seater. The GLB can be ordered with a small third row, making it one of the cheapest seven-seat luxury SUVs. The third row suits children only. For more space, compare the bigger models in our Mercedes 3-row SUV guide.
GLA vs GLB fuel economy
With the same engine, the lighter GLA is slightly more efficient: 29 mpg combined against 28 mpg for the GLB. Both require premium fuel, according to CarGurus.
Why is the Mercedes GLB so cheap?
The GLB is built on the same compact, front-wheel-drive-based platform as the GLA and the CLA, and uses the same 2.0-liter engine. That keeps its price well below larger Mercedes SUVs such as the GLC, even though it offers similar cargo space.
GLA vs GLB vs GLC dimensions
| Model | Length | Height | Max cargo | Seats |
|---|---|---|---|---|
| GLA 250 | 173.6 in | 63.5 in | 51 cu ft | 5 |
| GLB 250 | 182.4 in | 65.3 in | 62 cu ft | 5–7 |
| GLC 300 | 185.7 in | 64.6 in | 56.3 cu ft | 5 |
The GLC is the longest of the three, but the GLB has the most cargo space. See our GLB vs GLC comparison for the full picture.
Which is better, GLA or GLC?
The GLC is a size up, with more power and a more upmarket feel, but it starts at $50,800, about $9,300 more than the GLA. Choose the GLA if price and city driving matter most.
GLA vs GLB: which should you buy?
For singles, couples and city drivers, the GLA is the better buy. It is cheaper, more efficient and easier to park. For families, or anyone who regularly carries bulky items, the GLB is worth the extra $4,300 for its bigger cargo area and optional third row.
GLA vs GLB FAQs
Do the GLA and GLB have the same engine?
Yes. Both GLA 250 and GLB 250 use a 221-hp, 2.0-liter turbo four-cylinder with 258 lb-ft of torque.
Which is bigger?
The GLB. It is 182.4 inches long against 173.6 for the GLA, with 62 cubic feet of maximum cargo space against 51.
Which one has 7 seats?
Only the GLB, with its optional third row.
Which is cheaper?
The GLA, by about $4,300.
Which is better, Mercedes GLB or GLE?
The GLE is a much bigger, more expensive SUV starting at $63,500. The GLB suits buyers who want seven seats on a smaller budget.
Related reads
- GLB vs GLC: Price, Size, Third Row and Which Mercedes to Buy
- GLC vs GLE: 2026 Price, Size, Space and Which Mercedes to Buy
- Mercedes GLA 45 AMG: Why You Can’t Buy a New One in the US
- Mercedes SUV Models: The Full Lineup
For more Mercedes SUV guides, visit MercedesSUV.com.