Think of BMW's new M3 and M4 as fraternal twins with only a pair of doors to tell them apart.
Nearly everything else on these potent overachievers is the same, including 425 turbocharged horsepower and sub-four-second zero-to-60-mph runs.
After a white-knuckle week of testing both 2015 models, we were smitten by the four-door M3 but merely impressed with the two-door M4. Credit the sedan's extra dose of practicality — at no cost to style — and the sweet-shifting manual transmission that came in our test car. The M3 starts at $62,950 and wants for nothing.
Its lineage helps. As it has been for the previous four generations, the M3 is the high-performance version of BMW's 3-series family. BMW first launched the road-going M3 in 1986 to comply with racing regulations.
The original M3 was a coupe, but a few of the following generations have offered sedan and convertible variants. That continues here, except for the name: The sedan lives on as the M3, while the coupe and hardtop convertible are now badged as M4s.
Their rear-wheel-drive powertrains are identical. Wedged under the bulging aluminum hood of each is a 3.0-liter inline six-cylinder engine. It replaces the outgoing model's surly V-8 and uses turbocharging for the first time in the venerable model's history.
Though it lacks the pure vocals of the high-revving V-8, the twin-turbo six makes up for it in grunt. Horsepower is up a bit to 425, from 414, while torque is 406 pound-feet, a sharp increase from the old V-8's 295 pound-feet.
These new M cars went on a diet, using the smaller engine and carbon fiber and aluminum bits throughout to shed around 175 pounds. More power and less weight drop zero-to-60 mph times by 0.6 seconds.
An M3/4 with the standard six-speed manual transmission will do the run in 4.1 seconds, while cars with the $2,900 seven-speed dual-clutch transmission can pull off 3.9 seconds, according to BMW.
All that performance is adjustable too. The steering, the optional ($1,000) adaptive suspension, the dual-clutch transmission and the throttle input each have three modes.
A pair of configurable buttons on the steering wheel allow drivers to preset two combinations of all those modes. That's helpful, because the car reverts to a goofy default setup every time you fire it up.
Other high-tech options include an active limited-slip differential, stability control with a special dynamic mode, and a carbon fiber engine brace, trunk lid, roof and drive shaft. Those with unlimited budgets — or a desire to put the car on a race track — can add the $8,150 carbon ceramic brakes.
The manual transmission came with a light, precise shifter and automatic rev-matching on downshifts that felt like cheating; even the most ham-fisted driver could row it smoothly.
The automated dual-clutch on our M4 tester may be a tad faster, but the manual was much more fun, creating an intimate connection between driver and car. The manual also offered slightly better highway mileage, at 26 mpg instead of 24. Both versions are rated at 17 mpg in city driving.
We also preferred the higher seating position in the M3. Sitting lower in the M4 made it feel a bit more like a muscle car than a sport sedan.
Both models are athletic on the road, with endless power delivered in linear fashion. For maximum fun and control, turn off the overly conservative stability control software.
In curves, the M3 in particular felt lively and tactile. It's a car that still communicates the nuances of the roadway to the driver, a trait that's vanishing as cars get faster and more capable of doing most of the work for you.
The full brunt of torque comes on at a very low 1,850 revolutions per minute, so you need a deft touch on the gas pedal. The turbocharged engine never sounds great, but the noise gets better the harder you press it — partly because BMW pumps fake engine sound into the cabin through the stereo speakers.
The M3 combines asphalt-shredding power with the livability of a sedan and a comfortable back seat. Compared with the M4, it offers an extra inch and a half of headroom and legroom for back-seat passengers. Trunk space is also up by a cubic foot.
Our loaded test models weren't cheap: $81,425 for our M3, painted Yas Marina Blue, and $86,200 for the Austin Yellow M4. That included carbon ceramic brakes, the active suspension and LED lights, all of which are unnecessary.
Better to buy the base M3 for $62,950 or the base M4 for an additional $2,175.
So the sedan, more fun and functional, is also cheaper than the coupe. There's also something beautiful about a roomy sedan that can run with the Porsches.
They may be twins, but the M3 wins this sibling rivalry.