8 Series vs SL
Few matchups in the sports car class come up as often as the 8 Series against the SL. Think of it as a split decision: the 8 Series takes fuel economy & range, the SL takes engine & performance.
At a glance
- Engine & Performance SL wins
- Fuel Economy & Range 8 Series wins
- Space & Practicality Tie
- Off-road & Towing Tie
- Engine & Performance3.7
- Fuel Economy & Range4.1
- Engine & Performance4.7
- Fuel Economy & Range2.9
Spec scores (0 to 10) are calculated from manufacturer specs against other models in the same class. See how the formula works. They are not reviews or user ratings.
Key Differences
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The SL has 81 hp more power
This is one of the widest gaps in the whole comparison: 416 hp for the SL versus 335 hp for the 8 Series. More power helps with merging, overtaking and climbing hills, especially with passengers and luggage on board.
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The 8 Series has better fuel economy
The 8 Series gets a small bonus on fuel economy (combined), with 24 mpg against the SL’s 22 mpg. Better combined fuel economy lowers your running costs every week, and the savings add up over years of ownership.
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The 8 Series has better city fuel economy
Small gaps can still matter over time, and here the 8 Series leads 21 mpg to 19 mpg. In town, driving style has a big effect, but the 8 Series starts from a better baseline.
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The 8 Series has better highway fuel economy
The difference is minor (29 mpg against 27 mpg), but if you’re splitting hairs, the 8 Series wins it. The 8 Series uses less fuel on the highway, a real saving on road trips and long commutes.
Design & Size
Engine & Performance
SL leads
Look at the engine & performance table and one name keeps coming out on top: the SL. The SL stands out with 81 hp more power. The SL’s extra output gives it more in reserve when you need to get up to speed. On engine & performance alone, the SL gets the nod.
Total system output
8 Series: 335 hp SL: 416 hp Power is only part of the story; weight, gearing and torque delivery shape how quick a car feels.
Fuel Economy & Range
8 Series leads
This section belongs to the 8 Series. In fuel economy & range, it leads the SL by a margin that’s hard to ignore. In its favor, the 8 Series has better fuel economy. The 8 Series uses less fuel on the standard combined cycle, which matters most if you drive a lot. Net result: the 8 Series leads this part of the comparison.
Fuel economy (combined)
8 Series: 24 mpg SL: 22 mpg Official figures rarely match real-world driving exactly, but the ranking between two cars tends to hold.
Fuel economy (city)
8 Series: 21 mpg SL: 19 mpg City fuel economy matters most if your driving is mostly short trips, traffic and stop-and-go commutes.
Space & Practicality
Too close to call
The space & practicality specs are close enough that neither gets the point. Bottom line for space & practicality: it’s a wash.
Off-road & Towing
Too close to call
Call the off-road & towing round a draw. The takeaway: off-road & towing is not where these two differ.
Safety & Tech
For safety & tech, the spec sheet lists components and formats rather than figures we can rank. The table shows what the 8 Series and the SL each bring.
Full Specifications
Engine & Performance
| Spec | 8 Series | SL |
|---|---|---|
| Powertrain | Gas | Gas (48V mild hybrid) |
| Engine | 3.0L turbo I6 | 2.0L turbo I4 |
| Total system output | 335 hp | 416 hp (winner) |
| Torque | 368 lb-ft | 369 lb-ft |
| Transmission | 8-speed automatic | 9-speed automatic (AMG MCT) |
| Drivetrain | RWD (xDrive AWD available) | RWD (4MATIC+ AWD on V8 models) |
Fuel Economy & Range
| Spec | 8 Series | SL |
|---|---|---|
| Fuel economy (combined)EPA estimate where available | 24 mpg (winner) | 22 mpg |
| Fuel economy (city) | 21 mpg (winner) | 19 mpg |
| Fuel economy (highway) | 29 mpg (winner) | 27 mpg |
Space & Practicality
| Spec | 8 Series | SL |
|---|---|---|
| Seats | 4 seats | 4 seats |
Off-road & Towing
| Spec | 8 Series | SL |
|---|---|---|
| AWD / 4WD available | Yes | Yes |
Safety & Tech
| Spec | 8 Series | SL |
|---|---|---|
| Basic warranty | 4 yr / 50,000 mi | 4 yr / 50,000 mi |
“N/A” means the manufacturer does not specify the value or we could not confirm it. Figures marked “manufacturer rating” are the maker’s own claims, not our measurements.
Which One Should You Buy?
Choose the 8 Series if…
- you drive a lot and want lower running costs (24 mpg vs 22 mpg combined)
- you mostly drive in town (21 mpg vs 19 mpg in the city)
- you cover long highway distances (29 mpg vs 27 mpg on the highway)
Choose the SL if…
- you merge, overtake or climb hills with a full load (416 hp vs 335 hp)
- you’re comfortable with how Mercedes-Benz does things
Also Compared
Frequently Asked Questions
Should I buy the 8 Series or the SL?
The 8 Series and the SL split the comparison (fuel economy & range for the 8 Series, engine & performance for the SL), so pick the strength you’ll use.
Executive Summary
On paper, the 8 Series and the SL chase the same buyer. In the details, BMW and Mercedes-Benz made different calls. What I like most about the 8 Series here is better fuel economy. On top of that, the 8 Series adds better highway fuel economy. The SL has a trump card of its own in 81 hp more power.
If your days lean on fuel economy & range, I’d pick the 8 Series; if they lean on engine & performance, the SL.
My pick: I’d go with the 8 Series if I cared most about fuel economy & range, and the SL if engine & performance mattered more.
Personal opinion based on the data above. Your priorities may differ.