If BMW went through the trouble to break the 4-Series away from the 3-Series, you might expect a different driving personality. Well, that's not exactly the case, and this slightly lower, slightly more aggressive-looking Coupe or Convertible doesn't actually go through the paces much differently than the 3-Series. And that's fine, actually; it fires up sweetly engineered in-line engines, shifts with ease, and bear-hugs the road—all while plotting a clear trajectory into M territory with performance upgrades, and with the new M4.
The 4-Series lineup is definitely simpler than that of the 3-Series. There's no diesel, no hybrid, and no base-model 420i. There are two powerplants are on the order sheet, and you have to keep in mind that displacement no longer has anything to do with those numbers on the badge.
The 428i uses a 2.0-liter turbocharged four-cylinder to generate 240 horsepower and 255 pound-feet of torque. That puts it within reach of 60 mph in 5.7 seconds with either the manual or automatic transmission, with grippy summer tires. You also get a 155-mph, electronically limited top speed.
Step up to one of the 435i models and you get the familiar 3.0-liter turbocharged in-line six-cylinder engine, rated at 300 horsepower and 300 lb-ft. It's just as quick as the last-gen M3, with the 435i sprinting to 60 mph in 5.3 seconds with the manual transmission, or five seconds flat with the auto box.
With either engine, you get lump-free power delivery, and a gravy train of torque from just above idle to about 5000 rpm. It's quieter and smoother than the turbo four in the Cadillac ATS, and it pulls with a smoothness that builds on the recent past of naturally aspirated straight sixes.
With either engine, you can get rear-wheel drive or all-wheel drive; and yes, you can even get all-wheel drive on the Convertible. A six-speed manual transmission is a no-cost option on rear-drive coupes; it's an inspiring thing, with clean shifts and lovely clutch uptake. But with its eight gears spaced especially well to handle the six's torque spread, plus paddle shifters and sport driving modes, the automatic's technically better than rowing your own. Technically...but still not what we'd pick.
The path to that highly evolved 4-Series is clearly defined, from the way its suspension has been altered with more aluminum components and more structural stiffness than before. It still wants to be, and can be, a smooth grand tourer. The Driving Dynamics Control programming lets drivers tune shift points, throttle mapping, and steering response from a base level into an efficiency profile, and in either, it loafs along with rational, responsible moves.
But the 4-Series really feels most alive in the hands when it's spun into Sport or Sport+. The steering pounces into turns, the automatic snaps off almost instantaneous shifts, the throttle zips up and down the powerband. The stability control unlocks its chastity belt.
Of all the changes that have been wrought on the latest 3-Series and now in turn, the 4-Series, the electric power steering system has probably done the most to shake the foundations of the BMW faithful. The standard flavor weights up evenly but quickly, and with the larger wheel/tire combinations offered (up to 19 inches), the 4er's steering just feels heavier than it needs to, and follows the crown on the road more than it should. Feedback is sorely lacking. There's a premium Variable Sports steering setup that changes the rack's ratio; we haven't tried it yet in the standard 4-Series.
Yes, there's also the M4, and its hugely upgraded power ratings (now 425 horsepower and 406 lb-ft). With a TwinPower turbo six, a choice between six-speed manual and seven-speed M Double Clutch gearboxes, an Active M limited-slip differential, and an available Adaptive M suspension, the all-new 2015 BMW M4 takes after the larger M6 in ride and sophistication, yet it keeps its weight down, to enable a supercar-league 0-60 mph time of just 4.2 seconds (in DCT form).