By Jim Meachen and Ted Biederman

The M4 replaces the M3 in the BMW lineup, with slightly increased size and sleeker styling, and it's definitely a worthy successor with potent twin-turbo inline six-cylinder power that effectively replaces the V8 (downsized to enhance gas mileage), and slot-car-like handling. BMW created the 4 Series for the 2014 model year and added the coupe and convertible M editions for 2015.

Admittedly the M4 convertible has a certain attraction, but what's the point of paying extra ($8,300 more than the M4 coupe without options) for this M toy unless you plan on using it for its stated purpose? If unsure save the eight grand and go for the M4 Coupe, it’s actually a little faster because of a 525-pound weight advantage over the convertible, which lives with a heavy steel retractable roof.

Both coupe and convertible are quick, and fast. BMW says that with the seven-speed dual-clutch automatic the coupe will run from 0-to-60 in 4 seconds, the convertible in 4.2 seconds. We also drove one with the 6-speed manual shifter, which cuts two-tenths of a second off that time.

Regardless of configuration, the M siblings are the fastest and most powerful in the current 3 and 4 Series lineups and you’ll be rewarded with world-class performance. The twin-turbocharged 3.0-liter inline-6 developed for the M siblings produces 425 horsepower, and 406 foot-pounds of torque peaks at a low 1,850 rpm, that's an 11 horsepower gain and a boost in torque of a whopping 111 pound-feet over the outgoing V8. And peak torque is maintained over a very wide rev band (1,850–5,500 rpm). A bonus to the neck-snapping performance is the muscular throb of the engine as the twin-turbo spools up.

While we remain excited about driving a six-speed manual transmission — and the new M4 is one of the best we've encountered recently — we would soon tire of the constant need for shifting if we had to live with the car on tedious daily commutes in heavy traffic. Unless you are a super-shifter it's not possible to seamlessly go through the gears as fast as the automated 7-speed manual. Furthermore, during the 90 percent of driving that requires a more temperate attitude, the automatic turns the M4 into a very civilized easy-to-drive machine.

That's a good thing because this convertible is so head-turning gorgeous it draws attention to its low-slung stance, flared fenders, and the character line rising from the front fender to the rear taillight. Characteristic design elements leave no doubt that this car is the work of BMW M. The M edition also comes with unique front and rear aluminum suspension components, 19-inch forged alloy wheels, and has a two-inch wider stance than the standard 435i coupe and convertible.

The M4 convertible is not for the faint of heart when it comes to buying; prices start at $73,450 including destination charge. With a load of options — including the Executive Package ($3,500 for a heated steering wheel, forced-air neck warmer and other goodies), carbon ceramic brakes ($8,150) and adaptive suspension ($1,000) — our 6-speed car stickered out for a mind-blowing $88,725, and the dual-clutch automatic we tested topped out at $91,625.

Just so you know the traditional 4 Series convertible that makes 300-horses mated to an 8-speed automatic can be purchased for $17,870 less; that’s $55,580 in base trim. The standard version can also be ordered with all-wheel drive, a feature not available on the M.



The hard top on the BMW M4 Convertible features a number of design improvements that reduce noise levels for a much quieter interior ambience. And all it takes is the push of a button to transform a dynamic coupe into a convertible in a mere 20 seconds. The top can also be lowered when the vehicle is traveling at speeds of up to 11 mph.

One of the downsides to any convertible that stows a top in the trunk is lack of storage with the top down. When the top is up, the luggage compartment has a decent volume of 13 cubic feet, but that's reduced to a smallish 7.8 cubic feet when the top is stowed. On the plus side, a flat and level storage area can be utilized when the backrest of the rear bench seat is folded down. The load-through feature is standard in the U.S.

In addition to all of the go-fast goodies, the very cool droptop M4 also gets a host of standard and optional cutting-edge safety and driver assistance systems, including pedestrian collision warning, adaptive cruise control, and adaptive high beams designed to avoid blinding oncoming drivers.

Essentials
Base price: $73,450; as driven, $88,725
Engine: 3.0-liter twin-turbo inline 6
Horsepower: 425 @ 5,500 rpm
Torque: 406 foot-pounds @ 1,850 rpm
Transmission: 6-speed manual
Drive: rear wheel
Seating: 2/2
Wheelbase: 110.7 inches
Length: 183.9 inches
Curb weight: 4,055 pounds
Turning circle: 40 feet
Luggage capacity: 13 cubic feet
Fuel capacity: 15.8 gallons (premium)
EPA rating: 26 highway, 17 city
0-60: 4.4 seconds (manufacturer)
Also consider: Porsche Boxster GTS, Mercedes E63 Convertible, Audi RS 5 Convertible

The Good
• Outstanding performance
• World-class handling
• Stunning styling

The Bad
• Storage limited with top down

The Ugly
• Some key safety features come only as options