To purists (among them, engineers), driving the convertible version of a taut performance coupe is a little like seeking out the best gluten-free baguette in Paris. They gripe about the extra weight that comes in most convertibles and about the loss of torsional rigidity that comes when you lop off a car’s top half. In 1986, BMW made 5,000 of its new M3 performance coupes, mainly to qualify it for a distinguished race series. It took two years of customer requests before they made a drop-top M — probably after some BMW engineers lost their shit “compromising” their freshly minted masterpiece — but the heart wants what the heart wants.
Jump forward a quarter century and BMW’s hard-core sportster is now in its fourth generation, only now the two-door is the M4, while the four-door is the M3. And though the most brittle wing of the gearhead purist set may still scoff at a convertible iteration of its sporty golden child, we prefer it. Here’s why: Those same BMW engineers managed to erase the headaches and compromises once inherent in driving a convertible, from leaky roofs that were slow to rise to cabin acoustics that forced you to shout at Courtney Love decibels to aerodynamics that kept drop-top season to a fortnight everywhere but in the Sun Belt. And in regard to stiffness: BMW boosted it 60 percent over the previous generation. Click the adaptive suspension to Sport Plus mode, and ride as hard as your passengers’ intestinal fortitude will allow.
But the real reason for going topless: a visceral experience no hardtop can match. In open air, the sensation of speed is immense, and exhaust notes smack around underpass walls and straight into your cortex. Whale on the carbon-ceramic brakes and you can smell ’em. Under the domed hood is a relentless powerplant. Though the prior version carried a V-8, BMW opted for a twin-turbocharged inline-six engine. The result is more horsepower (425) much more urgently and bigger portions of torque available more of the time. So instead of waiting for peak power at high RPMs, you’re almost always in the engine’s sweet spot. Push it and the inline-six delivers a thick, hoarse wallop en route to a 4.2-second scramble to 60 miles per hour. The resulting Bavarian operetta isn’t dissimilar to an F1 race played through 5.1-channel surround. Yes, it sounds better with the top down.
Like the coupe, this M4 is loaded with high-tech smarts. A torque-vectoring differential doles out power to the rear wheel that needs it, enabling consummate traction. Adaptive LED headlights curve in the direction you’re steering, tempting you to go harder in the twisties after dark. And if you think your work behind the wheel is worth sharing, strap a GoPro to the hood, pair it wirelessly with the 10-inch touchscreen, and review your camera angles live.
But will you still love it after Labor Day? Sinatra called the summer wind a fickle friend, but he might as well have been talking about drop tops: The fun fades when you raise the roof. Of course, BMW’s engineers are all over delaying that moment, with aero tricks that divert wind around the cockpit to keep out the chill — and allow you to talk to your passenger without straining your vocal cords. Set up a windscreen and your hair remains almost intact. (This is a godsend for those of us with a forehead roughly the span of Alberta’s tar sands.) “Air collars” (basically vents), which force hot air down your back, appear for the first time in a BMW. You become impervious to the cold, like a surfer in Scotland wearing a six-millimeter wetsuit. The M4’s heated seats are so effective that you could set a frozen Hot Pocket on the passenger seat on your way home from work, and dinner would be ready by the time you arrived. Or better, eat it on the road, top down, well into football season. Leave it to the engineers to invent the endless summer.