Why You Can Trust CNET 2020 BMW M340i Sedan review: A dash of M makes everything better
A more powerful engine and nice chassis upgrades unlock more of the new 3 Series’ potential.
With the new, seventh-generation BMW 3 Series now in showrooms, I can't help but wonder when I'll be able to get my hands on the next M3 . Unfortunately, that won't be coming until next year at the earliest, but in the meantime, BMW has rolled out a hotter version of its new 3 series for 2020: the M340i. With more power, sharper handling and a mildly more aggressive look, can this M-lite car hold me over until that new M3 lands?
The Good
The Bad
The Bottom Line
Sweet turbo six
While the base 330i packs a 2.0-liter turbo-four with 255 horsepower, the M340i employs a 3.0-liter turbocharged I6 pumping out 383 horsepower and 369 pound-feet of torque. The latter is available throughout a large portion of the rev range, between 1,600 and 4,500 rpm. Disappointingly, BMW isn't offering a manual transmission in the new 3 Series, but a tried-and-true ZF-sourced eight-speed automatic is in charge of routing power to the wheels, and it does a fantastic job.
According to BMW, the M340i is good for 4.4-second sprints to 60 miles per hour, matching the Audi S4 and just edging out the 4.5-second efforts of the Genesis G70 3.3T and Mercedes-AMG C43. With how hard the M340i pulls off the line in its Sport Plus setting, the quoted number doesn't seem far fetched, either. Thrust is muscular throughout the rev band and the gearbox delivers well-timed and brisk cog swaps. For a more engaging driving experience, use the manual shift option with its steering wheel-mounted paddles. The do-it-yourself experience is responsive, the transmission rev-matches for downshifts, and it's all accompanied by an ear-pleasing, crackling exhaust soundtrack.
When you're not flogging it hard, the M340i is rated to return an EPA-estimated 22 miles per gallon in the city and 30 mpg on the highway.
M-like reflexes
To knock handling up a notch, the M340i improves on the standard 3 Series' foundation with a massaged suspension. This car gets firmer springs, thicker anti-roll bars, a lower ride height, more wheel camber, and 19-inch wheels wrapped with Michelin Pilot Sport 4S rubber. Throw in a standard torque-vectoring rear differential, as well as the optional adaptive dampers installed on my tester, and you've got an incredibly eager sports sedan.
Sport Plus tightens up the dampers and steering, resulting in crisp turn-in with a fair amount of feedback through the wheel. There's more than enough grip for enthusiastic runs around expressway interchange ramps and twisty back roads. While I'm very impressed with how the new Genesis G70 drives, the latest 3 Series convincingly solidifies its spot atop the luxury sports sedan heap as far as dynamics are concerned.
Thankfully, great handling doesn't mean the M340i compromises on ride quality. Selecting Comfort mode softens the shocks and relaxes steering for a perfectly nice and compliant ride around town. Bigger bumps still make themselves known inside the cabin, but typical road imperfections are absorbed without issue.
Sticky Michelin tires and larger brakes contribute to the M340i's improved handling prowess.
More style and tech
To visually set itself apart from the 330i, the M340i receives some light visual tweaks. You'll notice the larger air dams, and gray accents on the grille surround, mirrors caps and rear valance. Plus, the car rides on nifty split-spoke, M-specific wheels, which help drive home the sportier look.
Inside, the M340i gets supportive sport seats, a thick-rimmed leather steering wheel and aluminum trim. The layout is clean, the materials are of acceptable-but-not-great quality and there's sufficient room for passengers in both the front and back. The cabin is fine, but overall, the M340i's appearance and quality feel like half a step behind the Audi S4 and Mercedes C43.
There's not much to complain about the tech front, though. BMW's iDrive 7 unit oversees infotainment functions via a 10.2-inch touchscreen and center console-mounted controller. Both control options are intuitive and responsive, easily managing the onboard navigation, 16-speaker Harman Kardon surround sound setup, Bluetooth and Apple CarPlay. If you're an Android user hoping to read about BMW finally embracing Android Auto , I'm sorry to say today is not that day.
One thing not lacking in the M340i is all important power sources to charge phones and other smart devices. Passengers in front have access to a wireless charge pad, one USB-A and USB-C port, and a 12-volt outlet. In back there's another pair of USB-C outlets and a 12-volter mounted on the back of the center console.
For safety reasons, forward collision warning with automatic emergency braking comes standard on all M340is. Other active safety features such as adaptive cruise control, blind-spot monitoring and lane-departure warning with an aggressive active lane-keep assist function are available as options.
How I'd spec it
As with many German luxury vehicles, the M340i can get pricey in a hurry if you go too crazy. Case in point, my very well-equipped tester wears a $67,070 price tag, including $995 destination. That's a substantial leap over its $54,000 base price.
For my build, I'll begin with the rear-wheel-drive M340i and forego the available $2,000 xDrive all-wheel-drive hardware. I will pay $550 for a Portimao Blue Metallic paint job just like the car pictured here, and $700 for the adaptive suspension to have a wider handling range. To make it winter ready, I'll add the $1,400 Premium Package for a heated steering wheel and front seats, as well as the $300 remote engine start. Add on $875 for the Harman Kardon audio system and $500 for a Wi-Fi hotspot and wireless charge pad, and that brings my ideally spec'd car to $59,320.
Be careful with options. Get too out of hand and your M340i could end up costing $67,000 like this one.
Capable and compliant
While the 2020 BMW M340i isn't a thoroughbred M model, it represents quite a big step up from the base 330i. It's a hugely entertaining car that'll have you taking the long way home from work, and can be pleasant for mellow drives on congested roads. The ability to play the part of capable hard charger and compliant cruiser make it a sweet spot sports sedan.
If your plans call for frequent participation in autocrosses and track days, then waiting for the next M3 may be a good idea. But if it's mostly enthusiastic street drives and daily slogs, all the 3 Series you realistically need is on sale at your local BMW dealer.
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