X
CNET logo Why You Can Trust CNET

Our expert, award-winning staff selects the products we cover and rigorously researches and tests our top picks. If you buy through our links, we may get a commission. Reviews ethics statement

2021 BMW M440i Convertible review: An engaging cruiser

With a potent straight-six engine and refined-yet-crisp dynamics, this Bimmer drives better than you might expect for a ragtop luxury car.

Craig Cole Former reviews editor
Craig brought 15 years of automotive journalism experience to the Cars team. A lifelong resident of Michigan, he's as happy with a wrench or welding gun in hand as he is in front of the camera or behind a keyboard. When not hosting videos or cranking out features and reviews, he's probably out in the garage working on one of his project cars. He's fully restored a 1936 Ford V8 sedan and then turned to resurrecting another flathead-powered relic, a '51 Ford Crestliner. Craig has been a proud member of the Automotive Press Association (APA) and the Midwest Automotive Media Association (MAMA).
Craig Cole
5 min read
2021 BMW M440i Convertible - styling
Enlarge Image
2021 BMW M440i Convertible - styling

This car's front-end styling is slightly softer than BMW M3 and M4's. Do you like it any better?

Craig Cole/Roadshow

Unless it's something grand like a Rolls-Royce Dawn, I'm not much of a convertible fan. The added glare of top-down driving hurts my eyes; I don't like getting sunburned or having wind tussle my wispy hair; plus these cars are often noticeably shakier than their fixed-roof counterparts. But the 2021 BMW M440i Convertible is compelling enough to make even a droptop hater like me think twice.

7.8

2021 BMW M440i Convertible

Like

  • Impressive refinement
  • Strong acceleration
  • Silky inline-six

Don't like

  • Uneven low-speed braking
  • iDrive 7 could be simpler.
  • Brash front end

Naturally, this car's main attraction, and the feature that most clearly separates it from the 4 Series coupe, is its folding cloth roof. This is a new addition that replaces the previous convertible's hardtop. The redesigned assembly is about 40% lighter than before, which helps lower the center of gravity, though it also provides a tiny bit more headroom inside. Transitioning the M440i from enclosed car to open-air cruiser (or vice versa) happens in a curt 18 seconds, something you can do at speeds up to 31 mph.

Keeping the M440i's interior study-hall quiet, even at highway speeds, its folding soft top features a flush-mounted rear window and multiple layers of insulation. Additionally, the intake system, engine cover and underbody are tweaked to help minimize ruckus. The exterior fabric top is offered in two colors, basic black and Moonlight Black, the latter of which has a metallic shimmer.

2021 BMW M440i Convertible: Droptop fun plus driving refinement

See all photos

Two engines are offered in the 4 Series convertible and each is available with rear- or all-wheel drive. A 2.0-liter turbo-four motivates 430i models, though M440i variants like my tester feature a spicy 3.0-liter turbo I6. Truth be told, the base engine's 255 horsepower is probably more than enough, but it's impossible to argue with the optional six's 382 hp and 369 pound-feet of torque, which is routed to the pavement through an astute eight-speed automatic transmission. This combination can propel the M440i to 60 mph in 5 seconds flat, an impressive sprint time, though it feels even quicker than that. Depending on the wheel and tire combination, terminal velocity is either 130 mph or 155 mph, though with the top down both are probably fast enough to rip your hair plugs out. I already have enough exposed scalp to ever give this a try.

Making that up-level engine even more intoxicating is its silver-tongued exhaust note and incredible refinement. From idle to redline, the thing is smoother than hand lotion, transmitting basically zero vibration to the cabin. Aiding performance and fuel economy, this straight-six is augmented by a 48-volt electrical system, which also helps iron out stop-start events, making them nearly imperceptible. At lower speeds, the engine also shuts off and the M440i glides along, which is great, but without any load on the drivetrain it changes the brake-pedal feel, making it a bit of a challenge to stop smoothly at times. The M440i features M Sport Brakes including four-piston front calipers and single-pot rears, and this setup provides incredible stopping performance for everyday street use.

2021 BMW M440i Convertible - engine
Enlarge Image
2021 BMW M440i Convertible - engine

This 3.0-liter turbo-I6 is an absolute sweetheart, strong, sonorous and practically as smooth as an electric motor. 

Craig Cole/Roadshow

I'm almost ashamed to admit this, but I actually prefer the M440i convertible to the 2021 BMW M4. The car is still extremely quick and engaging without the manic, boiling-over feel of its overcaffeinated sibling. This droptop's front end, while still plenty -- let's just say distinctive -- is less in-your-face than what's fitted to the M3 sedan and M4 coupe. The front fascia is smoother and less pronounced around the top of kidney grilles and the titanium-colored accents (Cerium Gray in BMW parlance) look great, especially next to this example's deep Tanzanite Blue II Metallic paint, which is a $1,950 option.

The M440i's steering is quick and precise, and for better handling, the 4 Series convertible can be fitted with an Adaptive M Suspension system, which includes continuous damping adjustment at each wheel. But even with the stock suspenders this car is entertaining to drive, striking a great balance between sport and smooth. M440i examples also come with an M Sport Differential, which equalizes torque between the left and right rear wheels for better traction. This feature is optional on the less-potent 430i.

Whether the top is up or down, this Bimmer feels impressively sturdy. Structural shakes and jiggles are barely noticeable, even when driving over moon-cratered pavement, which is one of my primary complaints about convertibles . Fold the roof away to bask in Mother Nature's glory and the M440i provides a serene driving experience and a purring exhaust note that's pleasantly pronounced without being intrusive. Wind noise and buffeting are also well attenuated.

2021 BMW M440i Convertible

The 2021 BMW M440i Convertible's interior is bright and airy, suitably (if not overwhelmingly) luxurious, too.

Craig Cole/Roadshow

Even though it drives with a sharp edge, the M440i carries itself with dignity and restraint. This impressive refinement makes the car a bit deceptive, as you're always going faster than you think. Fortunately, all this speed does little to impact fuel economy. The M440i stickers at 23 mpg city and 31 mpg highway. Combined, it's rated at 26 mpg, though in mixed use I've been averaging 28 and change, damn impressive performance for such a potent and porky car (it is, after all, 4,171 pounds of Bavarian goodness).

Settle in behind the wheel and this BMW coddles you with an appropriately luxurious interior. This cabin doesn't blow my mind, but everything is sensibly laid out, the leather is of good quality and there are plenty of soft materials. The front bucket chairs are comfortable enough and the backseat, while it doesn't provide sprawl-out legroom, is still plenty spacious for adult passengers.

The 4 Series convertible comes standard with an 8.8-inch center touchscreen and a 5.1-inch instrument-cluster display. Live Cockpit Professional, which is offered as a standalone extra or bundled in several options packages, upgrades the main screen to a 10.3-incher and the gauge cluster to a 12.3-inch panel. The former is home to iDrive 7, an infotainment system that is blazingly fast but a little clunky. It's definitely not one of the easier systems to grasp, but once you do familiarize yourself it works well enough. If you don't feel like learning a new system, Apple CarPlay and Android Auto are both standard and, for added convenience, each smartphone-mirroring system can connect to the car wirelessly.

2021 BMW M440i Convertible - rear
Enlarge Image
2021 BMW M440i Convertible - rear

This M440i Convertible is ready for some fun in the sun.

Craig Cole/Roadshow

Other standard tech includes lane-departure warning with steering correction, forward collision warning, blind-spot monitoring and rear cross-traffic alert. Excellent automatic high beams are also included at no extra charge. Unfortunately, adaptive cruise control with stop-and-go capability and traffic jam assist as well as a 360-degree camera system and self-parking capability cost extra.

When it comes to dollars and cents, the 2021 BMW M440i Convertible starts around $65,000 including $995 in destination fees, which is about 11 grand richer than an entry-level 430i ragtop. With the $3,700 Executive Package, the $1,300 Dynamic Handling Package, an $875 Harman Kardon sound system and a few other ancillaries, this example checks out for $74,870.

With its silky six-cylinder engine, solid feel and crisp-yet-refined dynamics, the M440i is a good luxury car and an excellent convertible. Even though I still prefer enclosed vehicles, this droptop BMW puts a smile on my face nearly every time I drive it, a monumental achievement.

7.8

2021 BMW M440i Convertible

Score Breakdown

Performance 7.5Features 9Design 6.5Media 8.5