Mercedes GLB — MPG & Fuel Costs 2025
Mercedes' boxy, highly practical seven-seat SUV. Excellent interior packaging with sensible running costs.
The Mercedes GLB is a unique offering in the compact SUV segment, utilizing a boxy design to squeeze seven seats into a footprint similar to a standard B-Class.
Engines are shared with the A-Class, including a 1.3-litre petrol and a robust 2.0-litre diesel. It is available in both front-wheel-drive and 4MATIC all-wheel-drive layouts.
Real-world fuel economy is respectable, with the GLB 200d diesel returning 44 MPG in mixed use, while the GLB 200 petrol averages around 33-35 MPG.
TL;DR
33 MPG
Real-world petrol
44 MPG
Real-world diesel
52L
Tank capacity
£71.14
Full tank (petrol)
18.8p
Per mile (petrol)
Real-World Fuel Economy: The Mercedes GLB achieves an estimated 33 MPG (petrol) and 44 MPG (diesel) in real-world UK driving conditions, accounting for a 12% WLTP real-world penalty.
Forecourt Fuel Cost: Refueling the 52-litre tank completely costs approximately £71.14 (petrol) or £73.89 (diesel) at average UK fuel price rates.
Fuel economy at a glance
33
Real-world MPG
Petrol
39.2
Official WLTP
Petrol
44
Real-world MPG
Diesel
51.4
Official WLTP
Diesel
Annual fuel costs by mileage
| Annual mileage | Petrol | Diesel |
|---|---|---|
| 5,000 miles/yr | £942 | £734 |
| 7,400 miles/yr(UK average) | £1395 | £1086 |
| 10,000 miles/yr | £1885 | £1468 |
| 15,000 miles/yr | £2827 | £2202 |
| 20,000 miles/yr | £3769 | £2936 |
| Full tank (52L) | £71.14 | £73.89 |
| Cost per mile | 18.8p | 14.7p |
Based on UK average fuel prices: petrol 136.8p/L · diesel 142.1p/L. Prices updated regularly.
How does the GLB compare?
Tips to get better MPG from your GLB
The boxy shape increases aerodynamic drag; driving at 65 mph instead of 75 mph saves significant fuel.
Keep the rear seats folded flat when not in use to save weight and maximize load volume.
Avoid fitting roof boxes unless absolutely necessary, as they ruin the GLB's boxy aerodynamics.
Is the cheaper petrol station worth it?
In a Mercedes GLB achieving ~33 MPG real-world, if you fill 42 litres and the alternative station is 10p/litre cheaper:
£4.20
Gross saving on fuel
£0.57
Cost of 3-mile detour
£3.63
Net saving ✓
You could drive up to 22 miles round-trip before the saving disappears entirely.
Calculate for your exact situationPopular variants
Frequently asked questions
What is the real-world MPG of the Mercedes GLB?
The Mercedes GLB achieves approximately 33 MPG in real-world petrol driving — around 12% lower than the official WLTP figure of 39.2 MPG due to real driving conditions. Diesel variants achieve around 44 MPG real-world.
How much does it cost to fill a Mercedes GLB?
The Mercedes GLB has a fuel tank of 52 litres. At the UK average of 136.8p/litre for petrol, a full tank costs approximately £71.14. Diesel costs approximately £73.89 for a full tank.
What is the annual fuel cost for a Mercedes GLB?
At the UK average annual mileage of 7,400 miles and current petrol price of 136.8p/litre, a Mercedes GLB costs approximately £1395 per year in fuel. At 10,000 miles/year the cost rises to £1885. Actual costs vary with your driving style and mileage.
Is it worth driving to a cheaper petrol station in a Mercedes GLB?
In a Mercedes GLB doing ~33 MPG real-world, driving 3 miles round-trip to save 10p/litre on a 42-litre fill nets approximately £3.63 after the extra fuel cost. You could drive up to 22 miles before the saving is eaten up. Use the WorthThePump calculator for your exact situation.
How much does the Mercedes GLB cost per mile in fuel?
The Mercedes GLB costs approximately 18.8p per mile in petrol at current UK prices. Over a typical commute of 30 miles per day, that is approximately £5.64 per day in fuel.
What is the WLTP MPG figure for the Mercedes GLB?
The official WLTP fuel economy figure for the Mercedes GLB is 39.2 MPG. However, real-world MPG is typically 10–15% lower than WLTP due to cold starts, air conditioning, motorway speeds, and varying loads. WorthThePump uses a 12% real-world penalty to give a more accurate estimate.
Related guides
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