Used 2015 BMW M4 Base Convertible Review

The BMW M4 is a new model for 2015.

The 2015 BMW M4 is really an M3 coupe with a different name, a sleeker body and fewer doors. From track-day heroism to the daily commute, the M4 represents an ideal all-around two-door coupe or convertible for enthusiasts.

Last year BMW introduced its new 4 Series as the newly named version of what used to be the 3 Series two-door coupe and convertible. Now, for 2015, the company has brought out the performance version of that car, the new M4. It might be an unfamiliar name, but the performance and image fit right in with the legacy associated with the more familiar M3 name.

There is still an M3, actually, but it's now just the four-door sedan, and both cars feature the same M division upgrades. The transformation starts with the engine. There was a time when all M cars had naturally aspirated engines. But this time around, BMW has gone with a turbocharged 3.0-liter inline-6 that cranks out 425 horsepower and 406 pound-feet of torque. Both figures handily outgun the output from the 4.0-liter V8 used in the previous-generation M3 coupe and sedan. It's suitably aggressive and sounds like nothing else on the road.

Putting that power to the ground is either a standard six-speed manual or seven-speed dual-clutch automated manual transmission (M-DCT) that's connected to a carbon-fiber driveshaft and an electronically controlled limited-slip differential. This is the kind of specialized equipment once reserved for pure racecars, but now has trickled down to high-performance street cars such as the M4.

Other M-specific upgrades include unique front and rear fascias, aluminum suspension components, M-spec 18-inch forged alloy wheels, staggered wheel widths and optional six-piston carbon-ceramic brakes. The wider track also results in special body panels all around, including a hood and front fenders made of aluminum and a carbon-fiber roof. BMW says that only the door panels are shared with the 4 Series. Inside the car, it's like the more common 4 Series but with a decidedly more sporting look and feel.

The new M4 happens to be the freshest model compared with its traditional rivals. But you still owe it to yourself to also consider the aging but excellent Audi RS 5, which has the traction-enhancing benefit of all-wheel drive. The 2015 Mercedes-Benz C63 AMG coupe has also been around awhile, but its naturally aspirated V8 and accompanying soundtrack are highly addictive. If you want a slightly more relaxed approach to high performance, the new 2015 Lexus RC F should work out nicely. Finally, no discussion of high performance would be complete without mention of the superb 2015 Chevrolet Corvette. While it lacks a backseat, it does pack more performance per dollar than anything else on the road.

Any one of these specialized cars from their respective go-fast branches will certainly blow your hair back, but the 2015 BMW M4 coupe and convertible manage to strike that rare balance between docile, daily driver and nutty hooligan that we find so alluring.

The 2015 BMW M4 is a two-door, four-passenger high-performance car available in coupe or convertible body styles, based on the company's 4 Series.

The M4 includes 18-inch alloy wheels with summer tires, adaptive xenon headlights, auto-dimming mirrors, leather upholstery, heated 10-way power front seats (with four-way power lumbar), driver memory settings, fold-down rear seats, cruise control and dual-zone automatic climate control. Technology features include Bluetooth phone and audio connectivity, an 8.8-inch display screen, a navigation system, a suite of smartphone and online applications under the BMW ConnectedDrive banner, BMW's iDrive controller interface and a nine-speaker audio system with HD radio, a USB/iPod interface, an auxiliary audio jack and a CD player.

An optional Executive package adds headlight washers, front and rear parking sensors, keyless entry and ignition, a head-up display, a heated steering wheel, a rearview camera and satellite radio. The Lighting package further adds adaptive LED headlights and automatic high-beam control. The Driver Assistance package gets you blind-spot monitoring, lane-departure warning, a side- and top-view camera system, speed limit info, frontal-collision warning and automatic braking for collision mitigation.

Some items within the bundled packages are available as stand-alone options. Other stand-alone options include 19-inch wheels, upgraded carbon-ceramic brakes, adaptive suspension dampers, automated parallel-parking assist, extended- and full-leather treatments, a power rear sunshade, enhanced smartphone connectivity and a 16-speaker Harman Kardon surround-sound audio system.

On the coupe, you get your choice of either a visible carbon-fiber-reinforced-plastic (CFRP) roof or traditional steel roof with sunroof. In place of that roof, the M4 convertible has a power-retractable hardtop with a wind blocker, as well as extended leather upholstery and door trim that incorporates sun-reflective technology. When equipped with the Executive package (see above), it also includes front-seat neck warmers.

The M4 packs a turbocharged 3.0-liter inline six-cylinder engine that cranks out 425 hp and 406 lb-ft of torque. Compared to the previous M3, that's 11 more hp and 111 lb-ft more torque. The new engine still revs high, up to 7,600 rpm.

Two transmissions are available: a standard six-speed manual with automated rev-matching, or an optional seven-speed automated manual transmission (M-DCT) with steering-wheel-mounted paddle shifters. When equipped with the M-DCT and utilizing the integrated launch-control feature, the M4 will deliver a 0-60-mph time of 3.9 seconds (4.1 seconds for the convertible), according to BMW. At our test track, an M4 coupe with the manual transmission sprinted to 60 in 4.4 seconds.

Automatic engine stop-start (which shuts off the engine to save fuel while the car is stopped, such as when at a red light) is standard. The EPA estimates an M4 coupe with the manual transmission will deliver 20 mpg combined (17 city/26 highway). We recorded 25 mpg on our 120-mile Edmunds test loop. Opting for the automatic lowers efficiency by about 1 mpg across the board. Although it weighs about 500 pounds more than the coupe, the M4 convertible earns identical fuel mileage ratings numbers to the coupe.

Every 2015 BMW M4 comes standard with antilock brakes, traction and stability control, front side airbags, active front knee protection and rollover protection (convertible). The BMW Assist system for the M4 includes emergency services (SOS button and automatic collision notification), plus remote services (stolen-vehicle recovery and remote lock/unlock).

The stability control system integrates several features designed to improve braking performance, such as periodically wiping the brake rotors dry when the windshield wipers are in use and automatically snugging the pads to the rotors when the driver abruptly lifts off the gas. BMW Assist emergency communications is standard and includes automatic crash notification, stolen vehicle recovery and on-demand roadside assistance.

Optional safety features include rearview and top-down cameras, front and rear parking sensors, blind-spot monitoring, lane-departure warning, frontal collision warning (including pedestrian protection) and automatic braking for frontal collision mitigation. High-performance carbon-ceramic brake discs are also optional.

Simulated panic stops from 60 mph at our test track demonstrated the excellent capabilities of these optional brakes, with the shortest stop of 106 feet for an M4 coupe. This is a better-than-average performance.

Any driving impression of an M-badged BMW must start with the engine, and what an engine this is. It might not tingle the spine like the sonorous V8 did, but the new twin-turbo inline-6 is a gem in its own right. It not only produces more peak power than the outgoing engine, but also makes more everywhere in the engine's rev range. Throttle response is immediate and has a profound effect on how light and quick the car feels at any given moment. The M4 can be docile around town, but it'll still do the proverbial "smoky burnout" and chirp the tires between upshifts when you ask it to. It is true that the current trend of piping in an "amplified" version of engine/exhaust sounds through the car's stereo system is in full effect in the M4, but it doesn't sound computer-generated or disingenuous at all.

Another potential controversy involves the car's steering. Just like most new cars these days, the M4 uses electric-assist rather than traditional hydraulic-assist. The perceived problem is that electric-assist typically doesn't do as good a job of providing the driver feedback about what's going on at the front wheels. And sure enough, if you were to compare the new M4's steering feel to that of an M3 coupe of a couple generations ago (a car known for great steering feel), you'd come away disappointed. But the reality is that for the modern era, the system in the M4 is about as good as such systems go. It's highly responsive, exceptionally precise and isn't complicated by the company's controversial variable-ratio steering (that's available on other BMW products, but not here).

Much of the M4's deserved praise is due to the highly effective active differential that distributes power to the appropriate side depending on myriad variables. As such, the car's handling is more confident and capable than we've seen from any car bearing an M badge in years. If you're tempted to buy the adjustable suspension for fear the standard suspension might ride too hard, don't be worried. We found the standard suspension completely acceptable for daily use as well as amply fortified for exceptional handling performance. Also, the optional carbon-ceramic brakes don't often squeal and offer an unusual amount of pedal feel and feedback that are not typical of most cars with this option.

To shift or not to shift -- your own gears, that is. The M-DCT easily beats out the manual transmission in terms of quickness, smoothness and allowing the driver to concentrate on the task of driving. For pure driver involvement, though, the robust and slick-shifting six-speed manual is still the way to go, and it now includes (in some drive modes) automatic rev-matching for downshifts.

The 2015 BMW M4 gets the same general cabin design of the 4 Series, which is to say understated, though you do essentially get the 4's Technology package (navigation system, the larger display screen and the touchpad iDrive controller) as standard plus the requisite M badges and some snazzy carbon-fiber and aluminum trim. Overall it's solidly built and of high quality.

The company's classic analog gauges provide a historical link with BMWs of previous decades, while the optional head-up display provides digital information projected on the windshield. The standard iDrive interface is pretty easy to use, thanks to straightforward menus, crisp graphics and quick processing times. But compared with some rival systems, it typically requires a few more twirls and clicks to get what you want.

The front seats are both comfortable and supportive for aggressive driving, and there's plenty of front headroom and legroom. The backseat is decently sized for this class of car, with enough headroom and legroom for two average-size adults. Luggage space is generous, even in the convertible. Lowering the convertible's top takes about 20 seconds.