2025 BMW 3 Series M340i vs 2025 Mercedes-Benz C-Class C 300 4MATIC
2 mpg better and 131 more hp vs $9,750 less and AWD. That is the real fork. Key numbers: 386 vs 255 hp, 29 vs 27 MPG.
The 3 Series M340i leads on 2 MPG better, 131 more hp. The C-Class C 300 4MATIC leads on $9,750 less, AWD. The spec table compares 7 specifications head to head.
Key Differences at a Glance
What's Actually Different
These two vehicles differ in 7 specifications.
Full Specification Comparison
Specifications and pricing reflect available data as of early 2026 and may not match current manufacturer figures. Always confirm details with an authorized dealer before making a purchase decision.
| Spec | 2025 BMW 3 Series M340i | 2025 Mercedes-Benz C-Class C 300 4MATIC |
|---|---|---|
| Pricing | ||
| MSRP | $60,200 | $50,450 |
| Powertrain | ||
| Engine | 3.0L I6 mild-hybrid Turbo | 2.0L I4 mild-hybrid Turbo |
| Horsepower | 386 hp | 255 hp |
| Torque | 398 lb-ft | 295 lb-ft |
| Transmission | 8-speed shiftable automatic | 9-speed shiftable automatic |
| Drivetrain | RWD | AWD |
| Fuel Economy | ||
| City MPG | 27 | 24 |
| Highway MPG | 33 | 33 |
| Combined MPG | 29 | 27 |
| Fuel Tank | 15.6 gal | 17.4 gal |
| Annual Fuel Cost (EPA) | $2,000/yr | No published data |
| Dimensions | ||
| Curb Weight | 3,834 lbs | 3,957 lbs |
| Wheelbase | 112.2" | 112.8" |
| Length | 185.9" | 187.0" |
| Width | 71.9" | 74.4" |
| Height | 56.4" | 56.6" |
| Safety | ||
| NHTSA Overall | 5/5 stars | No published data |
| IIHS Award | No published data | TSP+ |
| Warranty | ||
| Bumper-to-Bumper | 4yr/50k | 4yr/50k |
| Powertrain | 4yr/50k | 4yr/50k |
| Corrosion | 12yr/unlimited | 4yr/50k |
| Roadside Assistance | 4yr/unlimited | 4yr/50k |
Frequently Asked Questions
What is the price difference between the 2025 BMW 3 Series M340i and 2025 Mercedes-Benz C-Class C 300 4MATIC?
The 2025 Mercedes-Benz C-Class C 300 4MATIC starts at $50,450, $9,750 less than the 2025 BMW 3 Series M340i at $60,200. On a 60-month loan that is roughly $172/month. All prices are MSRP before destination and dealer fees.
Who should choose the 2025 BMW 3 Series M340i?
The 2025 BMW 3 Series M340i is the stronger pick when lower running costs matter to you, roughly $108/year less on fuel; the extra 131 hp matters for your commute or driving style.
Who should choose the 2025 Mercedes-Benz C-Class C 300 4MATIC?
The 2025 Mercedes-Benz C-Class C 300 4MATIC is the stronger pick when you want to keep $9,750 in your pocket and the 2025 Mercedes-Benz C-Class C 300 4MATIC covers your needs; you drive in snow, rain, or unpaved roads where AWD keeps you planted.
Which gets better fuel economy, the 2025 BMW 3 Series M340i or 2025 Mercedes-Benz C-Class C 300 4MATIC?
The 2025 BMW 3 Series M340i rates 29 combined MPG, 2 MPG ahead.
Which is more powerful, the 2025 BMW 3 Series M340i or 2025 Mercedes-Benz C-Class C 300 4MATIC?
The 2025 BMW 3 Series M340i produces 386 hp, 131 more than the 2025 Mercedes-Benz C-Class C 300 4MATIC at 255 hp. The 2025 BMW 3 Series M340i also leads in torque at 398 lb-ft vs 295 lb-ft. The 2025 BMW 3 Series M340i runs a 3.0L I6 mild-hybrid Turbo; the 2025 Mercedes-Benz C-Class C 300 4MATIC uses a 2.0L I4 mild-hybrid Turbo. Drivetrains differ too: RWD on the 2025 BMW 3 Series M340i, AWD on the 2025 Mercedes-Benz C-Class C 300 4MATIC.
Is the 2025 BMW 3 Series M340i bigger than the 2025 Mercedes-Benz C-Class C 300 4MATIC?
The 2025 Mercedes-Benz C-Class C 300 4MATIC is 1.1″ longer at 187.0″ vs 185.9″. The 2025 Mercedes-Benz C-Class C 300 4MATIC has a 0.6″ longer wheelbase, which typically means more rear-seat legroom.
Do the 2025 BMW 3 Series M340i and 2025 Mercedes-Benz C-Class C 300 4MATIC have the same drivetrain?
No. The 2025 Mercedes-Benz C-Class C 300 4MATIC comes with AWD, while the 2025 BMW 3 Series M340i uses RWD. If you drive in snow, heavy rain, or on unpaved roads, the all-wheel or four-wheel drive option provides better traction. If you mostly drive on dry pavement, the two-wheel drive option saves fuel.
How do the warranties compare?
Both offer similar warranty coverage: 4yr/50k bumper-to-bumper and 4yr/50k powertrain.
Explore more: BMW trims, BMW 3 Series trims, Mercedes-Benz trims, Mercedes-Benz C-Class trims
The 3 Series–C-Class Decision
Shopping compact cars means the 3 Series and C-Class will likely end up on the same test-drive day. Here is what the numbers say before you get behind the wheel. The $-9,750 gap adds up to $172/month on a 60-month loan. That is real money, so the pricier option needs to earn it with capabilities you will actually use.
What Powers Each Vehicle
The 2025 BMW 3 Series M340i runs a 3.0L I6 mild-hybrid Turbo; the 2025 Mercedes-Benz C-Class C 300 4MATIC uses a 2.0L I4 mild-hybrid Turbo. The 2025 BMW 3 Series M340i has 131 more hp (386 vs 255). You will feel the difference merging, passing, and driving with a full car. The 2025 BMW 3 Series M340i adds 103 more lb-ft of torque (398 vs 295), giving it stronger low-end pull off the line. The 2025 Mercedes-Benz C-Class C 300 4MATIC comes with AWD; the 2025 BMW 3 Series M340i uses RWD. If you deal with snow, rain, or gravel roads, that traction advantage matters.
The Ownership Math
The 2025 BMW 3 Series M340i saves roughly $108/year on fuel at $3.50/gallon and 12,000 annual miles. Over five years, that is $540.
The Decision
Choose the 2025 BMW 3 Series M340i when lower running costs matter to you, roughly $108/year less on fuel. Choose the 2025 Mercedes-Benz C-Class C 300 4MATIC when you want to keep $9,750 in your pocket and the 2025 Mercedes-Benz C-Class C 300 4MATIC covers your needs.
Specifications shown combine licensed third-party automotive data with official manufacturer, EPA, and NHTSA source material. Actual pricing, features, and availability may vary by region and dealer. Always confirm details with an authorized dealer before making a purchase decision. TrimAtlas is not affiliated with BMW or Mercedes-Benz or any dealership.