4 Series vs SL
If you’re shopping for a car in the sports car class, the 4 Series and the SL are likely both on your shortlist. Think of it as a split decision: the 4 Series takes fuel economy & range, the SL takes engine & performance.
At a glance
- Engine & Performance SL wins
- Fuel Economy & Range 4 Series wins
- Space & Practicality Tie
- Off-road & Towing Tie
- Engine & Performance2.1
- Fuel Economy & Range7.2
- 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 161 hp more power
The SL clearly leads on total system output, and 416 hp versus 255 hp is a difference that reaches well beyond the spec sheet. The SL’s extra output gives it more in reserve when you need to get up to speed.
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The 4 Series has better fuel economy
On fuel economy (combined), the 4 Series posts 31 mpg against 22 mpg for the SL, a gap big enough to feel in everyday use. The 4 Series uses less fuel on the standard combined cycle, which matters most if you drive a lot.
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The SL has 74 lb-ft more torque
This is one of the widest gaps in the whole comparison: 369 lb-ft for the SL versus 295 lb-ft for the 4 Series. Electrified powertrains deliver torque instantly, so compare torque figures alongside the powertrain type.
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The 4 Series has better city fuel economy
The SL lists 19 mpg; the 4 Series comes in at 28 mpg. That’s not a rounding error. Hybrids often shine in the city, and the 4 Series has the better rating here.
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The 4 Series has better highway fuel economy
At 36 mpg versus 27 mpg, this is a decisive lead for the 4 Series, the kind of difference you notice without looking for it. Highway fuel economy matters if you cover long distances at steady speeds.
Design & Size
Engine & Performance
SL leads
This section belongs to the SL. In engine & performance, it leads the 4 Series by a margin that’s hard to ignore. In its favor, the SL has 161 hp more power. Power is only part of the story; weight, gearing and torque delivery shape how quick a car feels. Prioritize engine & performance, and the SL is where you should land.
Total system output
4 Series: 255 hp SL: 416 hp More power helps with merging, overtaking and climbing hills, especially with passengers and luggage on board.
Torque
4 Series: 295 lb-ft SL: 369 lb-ft More torque means stronger pulling from low speeds, which you feel when accelerating from a stop or climbing grades.
Fuel Economy & Range
4 Series leads
The 4 Series clearly takes the fuel economy & range round. The 4 Series stands out with better fuel economy. Official figures rarely match real-world driving exactly, but the ranking between two cars tends to hold. So if fuel economy & range tops your list, lean toward the 4 Series.
Fuel economy (combined)
4 Series: 31 mpg SL: 22 mpg Better combined fuel economy lowers your running costs every week, and the savings add up over years of ownership.
Fuel economy (city)
4 Series: 28 mpg SL: 19 mpg In town, driving style has a big effect, but the 4 Series starts from a better baseline.
Space & Practicality
Too close to call
On paper, the space & practicality comparison ends all square. Either car will serve you equally well on space & practicality.
Off-road & Towing
Too close to call
Swap one for the other and you’d lose nothing on off-road & towing. Net result on off-road & towing: level.
Safety & Tech
This section is descriptive. The 4 Series and the SL list different components for safety & tech, and the table spells them out.
Full Specifications
Engine & Performance
| Spec | 4 Series | SL |
|---|---|---|
| Powertrain | Gas (48V mild hybrid) | Gas (48V mild hybrid) |
| Engine | 2.0L turbo I4 | 2.0L turbo I4 |
| Total system output | 255 hp | 416 hp (winner) |
| Torque | 295 lb-ft | 369 lb-ft (winner) |
| Transmission | 8-speed automatic | 9-speed automatic (AMG MCT) |
| Drivetrain | RWD (xDrive AWD available) | RWD (4MATIC+ AWD on V8 models) |
Fuel Economy & Range
| Spec | 4 Series | SL |
|---|---|---|
| Fuel economy (combined)EPA estimate where available | 31 mpg (winner) | 22 mpg |
| Fuel economy (city) | 28 mpg (winner) | 19 mpg |
| Fuel economy (highway) | 36 mpg (winner) | 27 mpg |
Space & Practicality
| Spec | 4 Series | SL |
|---|---|---|
| Seats | 4 seats | 4 seats |
Off-road & Towing
| Spec | 4 Series | SL |
|---|---|---|
| AWD / 4WD available | Yes | Yes |
Safety & Tech
| Spec | 4 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 4 Series if…
- you drive a lot and want lower running costs (31 mpg vs 22 mpg combined)
- you mostly drive in town (28 mpg vs 19 mpg in the city)
- you want better highway fuel economy (36 mpg vs 27 mpg)
Choose the SL if…
- you want more power (416 hp vs 255 hp)
- you often drive loaded up or with a trailer (369 lb-ft vs 295 lb-ft of torque)
- you’re comfortable with how Mercedes-Benz does things
Also Compared
Frequently Asked Questions
Which is better for most people, the 4 Series or the SL?
Neither wins outright. Choose the 4 Series if fuel economy & range matters most, or the SL if engine & performance does.
Executive Summary
BMW makes the 4 Series, Mercedes-Benz makes the SL, and both want the same spot on your shortlist. Here’s where I land. The biggest reason I lean toward the 4 Series is simple: it has better fuel economy. Then there’s better highway fuel economy, another point for the 4 Series. I’ll admit the SL has a point with 161 hp more power.
Who should get which? The 4 Series for fuel economy & range, the SL for engine & performance.
My pick: the 4 Series for fuel economy & range, the SL for engine & performance, and no wrong answer between them.
Personal opinion based on the data above. Your priorities may differ.