Spawned a year ago from the ever-impressive 3 Series sedan, the BMW 4 Series coupe and convertible maintain a tradition of driving excellence. The 4 Series is costlier than the 3 -- almost four grand when new -- yet you get two fewer doors, largely analogous equipment and less practicality. Still, we feel the 2015 BMW 4 Series, with its more distinguishing presence, justifies its premium and fortifies BMW's position as a creator of exceptionally desirable luxury coupes and convertibles.

This BMW's low-slung, low-cabin stance is accentuated by flared fenders and a character line rising from the front fender to the rear taillights. The specs back up this visual impression: The 4 Series is about 2 inches lower to the ground than the sedan, and its wheels are pushed farther outward for improved handling stability and grip. Special styling details, such as vents in the front bumper fascia and in the fender just aft of the front wheels (BMW claims they improve aero efficiency) further differentiate the 4 Series.

Two efficient yet powerful engines are available. Base BMW 428i models get a turbocharged 2.0-liter four-cylinder rated at 241 horsepower and 258 pound-feet of torque. The numbers don't really tell the full story, though. In this new era of small-displacement turbocharged engines, BMW's is one of the best, providing easy around-town tractability along with surprisingly generous oomph when you nail the gas pedal. Should you want more, of course, there's the top-spec 435i model and its 300-hp, turbocharged 3.0-liter inline six-cylinder. If you live where foul-weather traction is a concern, any 4 Series variant is available with BMW's xDrive all-wheel-drive system.

Naturally, there are competitors lined up to take their best shots at the BMW. The most direct rival is the curvaceous 2015 Audi A5. Like the 4, it comes in coupe and convertible body styles and is powered by a stout and efficient four-cylinder engine. All-wheel drive is standard and its price is comparable to the BMW's. Another strong choice is the 2015 Mercedes-Benz C-Class Coupe, which is polished and refined in the way you expect a Mercedes to be. Finally, the Infiniti Q60 offers strong performance and value.

Still, the 4 Series -- with its excellent handling and performance, eye-catching styling and best-in-class interior room -- strikes us as the most complete and desirable luxury sport coupe and convertible available this year. That's why it has earned an Edmunds "A" rating in its class.

The 2015 BMW 4 Series is available as a two-door coupe and a retractable-hardtop convertible. There are two trim levels: 428i and 435i. Despite the misleading name, the 2015 4 Series Gran Coupe is, in fact, a four-door sedan and covered in a separate review.

Standard equipment for the 428i includes 17-inch wheels; adaptive xenon headlights; foglights; remote entry and push-button start; auto-dimming mirrors; a sunroof; leatherette (premium vinyl) upholstery; eight-way power front seats (with two-way power lumbar); driver memory settings; a leather-wrapped tilt-and-telescoping steering wheel; fold-down rear seats; dual-zone automatic climate control; a 6.5-inch display screen; BMW's iDrive electronics interface; BMW Assist; Bluetooth phone and audio connectivity; and a nine-speaker audio system with a USB/iPod interface, an auxiliary audio jack, HD radio and a CD player. In place of the sunroof, the 428i convertible has an automatic power-retractable hardtop with a wind blocker. Interestingly, the convertible includes folding rear seats -- a feature rarely seen in drop tops.

The 435i is equipped similarly but comes with a more powerful engine and 18-inch wheels.

Naturally, a wealth of options is available to help you customize your 4 Series. The Premium package equips the 4 Series with keyless ignition and entry (including a foot-activated trunk opening), four-way power lumbar for the front seats, satellite radio and leather upholstery. The Technology package adds a voice-controlled navigation system, a higher-resolution 8.8-inch display screen, a touchpad iDrive controller, a color head-up display, BMW Online with MyInfo (provides news and info to the car), BMW Apps (connectivity for select smartphone apps) and BMW Remote Services (allows select mobile devices to lock the car remotely, turn on the climate control and includes a stolen vehicle recovery service).

The Lighting package tacks on adaptive LED headlights and automatic high-beam control. A Cold Weather package adds heated front seats, a heated steering wheel and, for the convertible, front seat-mounted neck-warming air vents. The Driver Assistance package adds a rearview camera and front and rear parking sensors. Opting for the Driver Assistance Plus package gets you those features plus 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. Finally, the Dynamic Handling package furthers the 4 Series' capabilities with adaptive suspension dampers and automatic variable-ratio sport steering.

There are many stand-alone options as well. These include a live-operator concierge service, automated parallel-parking assist, upgraded brakes, a leather dashboard, a power rear sunshade, adaptive cruise control and a 16-speaker Harman Kardon surround-sound audio system.

Additionally, there are three optional equipment lines: Luxury (requires Premium package), Sport and M Sport. Each includes different wheel designs (up to 19 inches), various color schemes and unique trim and upholstery types. The Sport and M Sport also include M Sport suspension tuning, summer performance tires and 10-way sport front seats, while the M Sport further adds aerodynamic exterior trim and a sport steering wheel.

The 2015 BMW 4 Series comes with either rear-wheel drive or all-wheel drive ("xDrive"). For both body styles, an eight-speed automatic transmission is standard. A manual transmission is a no-cost option for the rear-drive coupes and the AWD 435i coupe. In order to save fuel, both transmissions come with an automatic stop-start function that turns off the engine when the car stops.

The 428i model uses a turbocharged 2.0-liter four-cylinder rated at 241 hp and 258 lb-ft of torque. In Edmunds testing, a coupe with the automatic transmission raced to 60 mph in just 5.4 seconds.

The EPA estimates for the 4 Series vary a little bit depending on whether you get the coupe or convertible and on which engine/transmission combo you opt for. An automatic-equipped rear-wheel drive 428i coupe is rated at 27 mpg combined (23 city/35 highway) and the manual transmission drops that down to 26 mpg combined (22/34). In the convertible (only available with an automatic) with RWD you're looking at 27 mpg combined (23/34) and with all-wheel drive that drops to 25 mpg combined (21/33). Pretty much all of these are outstanding numbers for the class.

The 435i has a turbocharged 3.0-liter inline six-cylinder engine rated at 300 hp and 300 lb-ft of torque. At our test track, a 435i coupe equipped with the six-speed manual charged from zero to 60 mph in 5.6 seconds, which is good for this class of car.

A 435i coupe with rear-wheel drive and the automatic transmission gets an EPA estimate of 25 mpg combined (22 city/32 highway) while the manual is rated at 24 mpg combined (20/30). If you want your 435i coupe with all-wheel drive (xDrive) the EPA estimates 24 mpg combined for the automatic and 23 mpg combined for the manual. On our test loop with a 435i xDrive coupe with the manual transmission, we achieved 28 mpg with ease.  

The convertible can only be had with an automatic transmission and is rated at 24 mpg combined (20/31) with RWD and 23 mpg combined (20/29) with AWD.

Every 2015 BMW 4 Series comes standard with antilock brakes, traction and stability control, front side airbags, side curtain airbags, front knee airbags and rollover protection (convertible). Simulated panic stops from 60 mph at our test track demonstrated excellent capabilities, with stops between 110 and 113 feet for the coupe on summer tires and with the optional M Sport brakes.

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.

A visit to the options list will provide parking sensors (front and rear), a rearview camera, top- and side-view cameras, blind-spot monitoring, a lane-departure warning system, attention assist, frontal-collision warning and automatic braking for frontal-collision crash mitigation (includes pedestrian detection).

The 2015 BMW 4 Series' sleek exterior look promises a lot in the way of excitement, and it largely delivers on BMW's "Ultimate Driving Machine" tag line. Though it's the less powerful of the two trims, you won't be disappointed with the 428i. Its four-cylinder engine delivers remarkably punchy and quick acceleration, along with an engaging engine and exhaust note that will have you winding up through the gears, fuel economy be damned.

The same can be said for the 2015 BMW 435i, but to an even greater extent. The traditionalist's choice in terms of transmissions will always be the manual, but the eight-speed auto works exceptionally well in both the normal driving mode or under the driver's control via the paddle shifters. In fact, our testing revealed that the 428i with the lightning-quick automatic transmission was quicker from zero to 60 mph than the more powerful 435i with the six-speed manual. Not by much, but that shows just how proficient this new eight-speed is. One annoyance is the gruff restart nature of the automatic engine stop-start function, though it can be disabled.

When the road bends, the 4 Series is marvelously balanced for a luxury sport two-door and easily instills driver confidence. The steering is very precise, but it lacks the detailed feedback that made older BMWs feel special.

Some might find the ride quality overly firm, but opting for the Dynamic Handling package's driver-selectable adaptive suspension nearly erases road imperfections while further boosting the car's stability.

The 4 Series might be a new model designation, but the cabin is all 3 Series, with a classy design and premium materials. The company's classic analog gauges provide a historical link with BMWs of previous decades, while the Luxury, Sport and M Sport give you plenty of leeway to customize the cabin to your taste.

In terms of technology, the basic 6.5-inch display screen is adequate, but you'll want to get the larger, optional screen for a true luxury-electronics interface. Overall, iDrive is pretty easy to use, thanks to straightforward menus, crisp graphics and quick processing times. But compared to some rival systems, it typically requires a few more twirls and clicks to get what you want.

A lower seating position than in the sedan helps add to the sporting persona of the BMW 4 Series. Even the standard front seats are very supportive and comfortable, and good both for long road trips and spirited driving. There's also an impressive amount of legroom, and enough headroom for average-sized adults in back. Luggage space is generous, even in the convertible. Lowering the convertible's top takes about 20 seconds.