Mercedes CLS — MPG & Fuel Costs 2025
The original four-door coupe, combining the elegance of a coupe with E-Class luxury and space.
The third-generation Mercedes CLS is a sleek four-door saloon that pioneered the 'four-door coupe' segment. Built on the executive E-Class chassis, it features frameless doors and a luxurious interior.
Engine choices are highly advanced, including Mercedes' latest inline four and six-cylinder diesel engines. The CLS 300d uses a twin-turbo four-cylinder to deliver excellent fuel efficiency.
Real-world fuel economy is highly impressive for a large executive car, with the CLS 300d diesel averaging around 42-45 MPG, while the smooth CLS 400d V6 diesel returns 38-40 MPG.
TL;DR
29 MPG
Real-world petrol
42 MPG
Real-world diesel
66L
Tank capacity
£90.29
Full tank (petrol)
21.4p
Per mile (petrol)
Real-World Fuel Economy: The Mercedes CLS achieves an estimated 29 MPG (petrol) and 42 MPG (diesel) in real-world UK driving conditions, accounting for a 12% WLTP real-world penalty.
Forecourt Fuel Cost: Refueling the 66-litre tank completely costs approximately £90.29 (petrol) or £93.79 (diesel) at average UK fuel price rates.
Fuel economy at a glance
29
Real-world MPG
Petrol
34.5
Official WLTP
Petrol
42
Real-world MPG
Diesel
50.4
Official WLTP
Diesel
Annual fuel costs by mileage
| Annual mileage | Petrol | Diesel |
|---|---|---|
| 5,000 miles/yr | £1072 | £769 |
| 7,400 miles/yr(UK average) | £1587 | £1138 |
| 10,000 miles/yr | £2144 | £1538 |
| 15,000 miles/yr | £3217 | £2307 |
| 20,000 miles/yr | £4289 | £3076 |
| Full tank (66L) | £90.29 | £93.79 |
| Cost per mile | 21.4p | 15.4p |
Based on UK average fuel prices: petrol 136.8p/L · diesel 142.1p/L. Prices updated regularly.
How does the CLS compare?
Tips to get better MPG from your CLS
The CLS has a highly aerodynamic, swept-back body; keep speeds consistent on motorways to exploit this.
For CLS 450 mild-hybrids, drive smoothly to maximize energy recovery during coasting.
Ensure tyre pressures are adjusted correctly for wide staggered rear wheels.
Is the cheaper petrol station worth it?
In a Mercedes CLS achieving ~29 MPG real-world, if you fill 53 litres and the alternative station is 10p/litre cheaper:
£5.30
Gross saving on fuel
£0.64
Cost of 3-mile detour
£4.66
Net saving ✓
You could drive up to 25 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 CLS?
The Mercedes CLS achieves approximately 29 MPG in real-world petrol driving — around 12% lower than the official WLTP figure of 34.5 MPG due to real driving conditions. Diesel variants achieve around 42 MPG real-world.
How much does it cost to fill a Mercedes CLS?
The Mercedes CLS has a fuel tank of 66 litres. At the UK average of 136.8p/litre for petrol, a full tank costs approximately £90.29. Diesel costs approximately £93.79 for a full tank.
What is the annual fuel cost for a Mercedes CLS?
At the UK average annual mileage of 7,400 miles and current petrol price of 136.8p/litre, a Mercedes CLS costs approximately £1587 per year in fuel. At 10,000 miles/year the cost rises to £2144. Actual costs vary with your driving style and mileage.
Is it worth driving to a cheaper petrol station in a Mercedes CLS?
In a Mercedes CLS doing ~29 MPG real-world, driving 3 miles round-trip to save 10p/litre on a 53-litre fill nets approximately £4.66 after the extra fuel cost. You could drive up to 25 miles before the saving is eaten up. Use the WorthThePump calculator for your exact situation.
How much does the Mercedes CLS cost per mile in fuel?
The Mercedes CLS costs approximately 21.4p per mile in petrol at current UK prices. Over a typical commute of 30 miles per day, that is approximately £6.42 per day in fuel.
What is the WLTP MPG figure for the Mercedes CLS?
The official WLTP fuel economy figure for the Mercedes CLS is 34.5 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
Find the cheapest fuel for your CLS
Enter your registration and we'll calculate whether the cheaper station nearby is worth the detour — factoring in your CLS's real-world MPG.
Try WorthThePump — it's free