3 Series Research for Northern California
2026 BMW M340i vs BMW M3
The same inline-six family, two very different missions. One is a fast sedan you live with. The other is a motorsport car with back seats.
The 2026 BMW M340i and the BMW M3 both use a 3.0-liter turbocharged inline six-cylinder, and both wear an M badge of some kind. That is roughly where the similarity stops. The M340i is a 386-horsepower 3 Series with M hardware, starting at $62,300 MSRP. The M3 is a purpose-built BMW M car with a different engine, from 473 to 523 horsepower, starting at $78,400 MSRP.
At BMW of Napa Valley, we sell both, so this page is not an argument for one over the other. It is a description of two genuinely different cars, so you can tell which one you actually want. We serve Solano County and Northern California, from Vacaville and Vallejo to American Canyon, right off I-80.
The Fast Sedan
2026 BMW M340i Overview
The M340i is the top of the regular 3 Series lineup. Its 3.0L M TwinPower Turbo inline-six makes 386 horsepower and 398 lb-ft, with 48-volt mild-hybrid assistance and an 8-speed automatic. Rear-wheel drive is standard and xDrive all-wheel drive is available for $2,000. In xDrive form it reaches 60 mph in about 4.1 seconds, and it returns an EPA-estimated 29 MPG combined. It comes standard with an M Sport Differential, M Sport Brakes, and 19-inch wheels.
Pricing starts at $62,300 MSRP, or $64,300 MSRP with xDrive. Full equipment detail is on our 3 Series trims page.
The M Car
2026 BMW M3 Overview
The M3 is built by BMW M, not adapted from the 3 Series. Its S58 twin-turbocharged 3.0L inline-six is a different engine from the M340i's, and it comes in three states of tune. The base M3 makes 473 horsepower and 406 lb-ft through a 6-speed manual and rear-wheel drive, the only M3 you can get with three pedals, starting at $78,400 MSRP. The M3 Competition makes 503 horsepower and 479 lb-ft through an 8-speed automatic, rear-wheel drive, from $82,600 MSRP. The M3 Competition xDrive makes 523 horsepower with M xDrive all-wheel drive, which includes 4WD, 4WD Sport, and rear-drive-only 2WD modes, from $87,700 MSRP.
Efficiency is the cost of that engineering: the EPA rates every M3 at 16 MPG city / 23 MPG highway, with 19 MPG combined in rear-drive form and 18 MPG combined for the Competition xDrive.
Under the Hood
Powertrain Comparison
| Measure | BMW M340i | BMW M3 |
|---|---|---|
| Engine | 3.0L M TwinPower Turbo inline-six, 48V mild hybrid | 3.0L M TwinPower Turbo (S58) twin-turbo inline-six |
| Horsepower | 386 horsepower | 473, 503, or 523 horsepower by trim |
| Torque | 398 lb-ft | 406 lb-ft (base) or 479 lb-ft (Competition) |
| Transmission | 8-speed automatic | 6-speed manual (base) or 8-speed automatic |
| Drivetrain | Rear-wheel drive standard; xDrive $2,000 | Rear-wheel drive; M xDrive on Competition xDrive |
| 0-60 mph | About 4.1 seconds (xDrive) | 4.1 seconds (base), 3.8 (Competition), 3.4 (Competition xDrive) |
| EPA combined | 29 MPG combined, EPA-estimated | 19 MPG rear-drive, 18 MPG Competition xDrive, EPA-estimated |
One number deserves a second look. The base M3 makes 87 more horsepower than the M340i, yet both reach 60 mph in about 4.1 seconds, the M340i in xDrive form and the M3 with a manual gearbox and rear-wheel drive. Straight-line acceleration is not why you buy the base M3. You buy it for the manual, the rear-drive purity, and the chassis. If outright speed is the goal, the M3 Competition xDrive's 3.4 seconds is where the M3 pulls decisively ahead.
Hardware
Chassis, Hardware, and Daily Livability
The M340i carries M Sport hardware on a 3 Series structure: an M Sport Differential, M Sport Brakes, 19-inch wheels, and a suspension tuned to stay comfortable on a commute. The M3 is engineered by BMW M from the ground up, with M-specific suspension, brakes, and cooling, and on the Competition xDrive an all-wheel-drive system that lets you send all power to the rear wheels.
Both cars share the 3 Series body's practicality: 16.9 cubic feet of trunk, five seats, and a 14.9-inch central touchscreen. Both come with a 4-year/50,000-mile warranty. On a Northern California commute, the M340i's ride and 29 MPG combined ask less of you every day. On a canyon road or a track day, the M3 does things the M340i cannot.
The Money
Pricing and Availability
Every figure below excludes destination, so they compare directly. The step from an M340i to a base M3 is $16,100.
| Build | Power | Starting MSRP (excludes destination) |
|---|---|---|
| BMW M340i | 386 horsepower | $62,300 MSRP |
| BMW M340i xDrive | 386 horsepower | $64,300 MSRP |
| BMW M3 | 473 horsepower, manual | $78,400 MSRP |
| BMW M3 Competition | 503 horsepower | $82,600 MSRP |
| BMW M3 Competition xDrive | 523 horsepower | $87,700 MSRP |
MSRP excludes destination, tax, title, license, and dealer fees. Pricing and equipment can change; confirm current pricing with the dealership.
A note on availability. We stock the M340i regularly. The M3 is a limited-production M car and we rarely have one on the ground, so an M3 is normally an allocation and order conversation rather than something you drive home the same afternoon. This generation of M3 is also late in its life cycle, which tightens allocation further. If you want one, talk to us early.
The M340i Case
Where the M340i Wins
1. Efficiency, by a wide margin. An EPA-estimated 29 MPG combined against the M3's 19 MPG rear-drive or 18 MPG Competition xDrive. Over a daily commute that difference is real money and fewer stops.
2. Everyday comfort. The M340i's suspension is tuned for the commute first. It is the easier car to live with in traffic, on broken pavement, and on a long interstate run.
3. You can buy one now. We stock M340i sedans. The M3 usually requires an allocation and a wait.
4. xDrive without the performance premium. All-wheel drive is a $2,000 option on the M340i. In the M3, all-wheel drive arrives only on the Competition xDrive, the most expensive trim in the lineup.
The M3 Case
Where the M3 Wins
1. A different engine and far more of it. The S58 is BMW M's own twin-turbo six, making 473, 503, or 523 horsepower. The Competition xDrive reaches 60 mph in 3.4 seconds, a gap the M340i cannot close.
2. A manual transmission. The base M3 is the only car in this comparison offered with a 6-speed manual and rear-wheel drive. Nothing in the 3 Series lineup replaces that.
3. Purpose-built M engineering. M-specific suspension, brakes, and cooling, developed for sustained hard driving. On the Competition xDrive, M xDrive lets you select 4WD, 4WD Sport, or send everything to the rear wheels in 2WD mode.
4. It is an M car. The badge is not decoration. The M3 is engineered by BMW M for the track and holds its character on the road; the M340i is a superb 3 Series wearing M hardware. If you want the real thing, only the real thing will do.
Buyer Guide
Which Should You Choose?
We sell both. Neither is the smart choice or the indulgent one; they answer different questions.
| If You | Choose | Why |
|---|---|---|
| Want to shift your own gears | BMW M3 | The base M3 is the only one here with a 6-speed manual. |
| Drive track days or want maximum acceleration | BMW M3 Competition xDrive | 523 horsepower and 3.4 seconds to 60, with M-specific cooling and brakes. |
| Commute daily and still want a fast six-cylinder | BMW M340i | 386 horsepower with an EPA-estimated 29 MPG combined and a livable ride. |
| Want all-wheel drive on a fast sedan | Either | M340i xDrive at $64,300 MSRP, or M3 Competition xDrive at $87,700 MSRP with 523 horsepower. |
| Need the car this month | BMW M340i | We stock it. An M3 is usually an allocation and an order. |
| Have wanted an M car for years | BMW M3 | Buy the car you actually want. This generation will not be built forever. |
If you are not sure, drive an M340i first. It answers the question of whether 386 horsepower is enough, and it is on our lot today. If the answer is no, you already know you want the M3. Compare the wider lineup on our 3 Series trims page, or see every specification on the specifications page.
Decide for Yourself
Drive an M340i, Order an M3
We typically carry the M340i, so you can drive one at our Fairfield showroom this week. M3 sedans reach us in small numbers and move quickly, so the practical route to one is an allocation conversation with our team. Tell us the trim, the transmission, and the colors you want, and we will tell you honestly what is possible and when. Call (707) 402-1500 or contact our team.
Answers
M340i vs M3 FAQs
Is the M340i an M car?
No. The M340i is the top of the regular 3 Series lineup, fitted with M Sport hardware including an M Sport Differential and M Sport Brakes. The M3 is engineered by BMW M with its own S58 twin-turbocharged engine, suspension, brakes, and cooling.
How much faster is the M3 than the M340i?
It depends on the trim. The base M3 reaches 60 mph in 4.1 seconds, the same as the M340i xDrive, despite making 87 more horsepower, because it uses a manual gearbox and rear-wheel drive. The M3 Competition does it in 3.8 seconds and the M3 Competition xDrive in 3.4 seconds.
What is the price difference between the M340i and the M3?
The M340i starts at $62,300 MSRP and the base M3 at $78,400 MSRP, a difference of $16,100. Both figures exclude destination. The M3 Competition starts at $82,600 MSRP and the M3 Competition xDrive at $87,700 MSRP.
Can you get a manual transmission in the M340i?
No. The M340i comes only with an 8-speed automatic. The base M3 is the only car in this comparison offered with a 6-speed manual transmission, paired with rear-wheel drive.
Which gets better fuel economy, the M340i or the M3?
The M340i, clearly. It is EPA-estimated at 29 MPG combined. The M3 is EPA-rated at 16 MPG city and 23 MPG highway, with 19 MPG combined in rear-drive form and 18 MPG combined for the Competition xDrive.
Is the BMW M3 in stock at BMW of Napa Valley?
Rarely. The M3 is a limited-production M car, so we usually order one to your specification through an allocation rather than sell one from the lot. We do stock the M340i regularly. Contact our team to discuss M3 availability and timing.
Talk M Cars With Our Team
BMW of Napa Valley, 2399 Auto Mall Pkwy, Fairfield, CA. Call (707) 402-1500 or start online.