Head to head · G20 vs G80
M340i vs M3: which one should you buy?
The value benchmark against the full M car: a classic cross-shop in the modern BMW range. Most comparisons stop at the spec sheet. This one scores both cars the way we score everything and names the reliability gap the spec sheets ignore.
The scores, side by side
| Score | M340i G20 | M3 G80 |
|---|---|---|
| Guide Score, best years 2022 and 2026 | 71 | 91 |
| Desirability | 66 | 81 |
| Enthusiast | 64 | 94 |
| Reliability (B58 vs S58) | 89 | 89 |
The case for the M340i
Near-M3 pace for far less used money. The B58, one of BMW's most reliable modern engines, does the work, and the car brings comfortable daily manners and running costs a sane person can budget.
It is the default cross-shop against the C43 and S4 for a reason. For most people who want a fast, comfortable daily, the M340i is the correct car.
The same estimates as each car's guide page. M-car insurance comes on top for the M3.
The case for the M3
It is the M car. The S58; the M chassis, steering and differential; the optional manual; the wider track. The M340i approximates each of them, and the spec sheet barely captures the way the M3 moves.
It leads on desirability, leads the driving score by a wide margin, and holds enthusiast attention and value in a way no 340 ever will. Hence the much higher Guide Score.
The verdict
M340i
Daily driver with occasional fun, budget matters, want to service it and forget it: M340i, and do not look back.
M3
Weekend car, track days, the manual matters, or you know the badge will quietly bother you forever: M3, budgeted properly.
To run the numbers side by side with the verdict weights set your way, use the compare tool.
Go deeper
- M340i G20 full guide (and the post-LCI version, see what LCI means)
- M3 G80 full guide
Questions and answers
Is the M340i as good as an M3?
In a straight line it is close: BMW quotes 0 to 60 mph in 4.2 seconds for the M340i xDrive, 4.1 for the manual M3 and 3.4 for the M3 Competition xDrive, and the M340i costs about half as much used. It is the more comfortable daily, and its B58 is one of BMW's most dependable engines (on 2020 and 2021 cars, check the oil pump history). What it lacks is the M3's chassis (M-specific suspension and steering, an Active M differential, a wider track), the manual option, and the motorsport pedigree. Which side of that trade matters more is the whole decision.
Is the M340i more reliable than the M3?
By engine family, yes. The M340i's B58 is widely regarded as one of BMW's most reliable modern engines, though 2020 and 2021 cars carry an oil pump risk. The G80 M3's S58 has a good record so far, with no equivalent of the S55's crank hub worry, but it is a higher-strung M engine with more aggressive cooling and turbo demands, especially on tracked cars.
Which is cheaper to own, an M340i or an M3?
The M340i, meaningfully. Our estimates put its routine service at $350 to $700 a year with tires at $900 to $1,500 a set, against $450 to $1,000 and $1,500 to $2,100 for the G80 M3, whose brake jobs run up to $3,400 against $1,600, with M-car insurance on top.