It's always a bit ironic when you tell people that chopping off the roof will make a car gain weight. We're speaking figuratively, of course, but all the delicate engineering to make a hardtop roof retract and stow away amounts to increased weight and a loss of structural rigidity. The heavy three-piece metal roof, the hinges, latches, motors, and hydraulics - everything adds up. In the case of the M4 Cabriolet, the penalty is 250 kg over the M4 Coupe. That's like lugging around four average-sized human (dead?) bodies in the back of your car.

Added weight is a nightmare to enthusiasts, which is why the M4 Coupe seems like the more appealing companion. It has a fixed and very rigid carbon fibre roof panel, it weighs less, and it's faster. Both variants get a sweet high-revving twin-turbocharged straight-six good for 425 horsepower and 406 lb-ft of torque, but the weight disadvantage means the Cabriolet reaches 0 - 100km/h in 4.4 seconds, 0.3 seconds slower than the Coupe.

The bad news continues. All that extra space needed to stow away the retractable roof means a lot of useable trunk space had to be sacrificed. The M4 Cabriolet has 20 L more cargo room than the previous generation M3 Cabriolet but the maximum still tops out at 370 L top up and 220 L top down. Maybe a few small backpacks will squeeze into the prison cell they call a trunk, but don't expect to fit large suitcases or actual dead bodies with the roof down. You can however, fold the rear seats flat to squeeze elongated items such as your skis and golf clubs inside. And if you're inquiring about the price premium for that foldable top, it's $9,500 more than the M4 Coupe, and $15,400 more than a 435i xDrive Cabriolet.

I know. I haven't mentioned anything good about the M4 Cabriolet as of yet. I guess this is a sort of bad-news-first review. I wanted to get all that babble out of the way because most M4 Cabriolet owners aren't going to care about 0-100 km/h numbers, or the curb weight, or that it doesn't have the same structural rigidity as the Coupe. In their world, driving pleasure comes first. The noise, the attention, the bittersweet aroma of burnt rubber; it is the culmination of all these sensory stimulants that makes the M4 Cabriolet such a wonderful car.

It's hard to put into words how it feels to drive an M4 without a roof. There's a sense of occasion to it. Driving becomes more of an event than a daily chore and your body will be thanking you with a healthy dose of Vitamin D. Some people say they feel "naked" driving a convertible, referring to the fact that everyone will be staring at you, but as a matter of fact, I feel more alive. I feel less confined to a tight cabin with its fancy buttons and blinking lights. There's a whiff of open-air freedom. Seeing as we're already limited in convertible-friendly weather here in Toronto, it's nice to know that when the stars align, there's a 420-hp beast awaiting the input of your right foot. With the top down, you have front row seats to one of the most charismatic engines produced by BMW. Nothing will replace the yowling 4.0-litre V8 from the previous generation M3, but the M4 tries its best with a lower octave bellow. Listen hard and you'll even hear some turbos spooling up.

On the bright side, novice eyes will think it's just another 3-series or 4-series - a favourable trait if you're not one to enjoy the attention. Miss the cues and it will fly under your radar: the lower profile, larger front intakes, wider side skirts, unique fenders, a quad-pipe exhaust, and the obvious M4 badging. Now if you regularly follow our reviews, you might be wondering why it's the same colour as the 435i Cabriolet we tested a few weeks ago. A keen eye would spot the difference in the paint. Our 435i Cabriolet donned the more opaque Alpine White, while our M4 Cabriolet wears the Mineral White paint. The latter is considered the "dirtier" white, as it's not as sleek or as vibrant as the former. There are subtle sparkles in the tint but it only looks rich and uniform from certain angles. Regardless, the two whites are almost indistinguishable at night. My vote is still on the Alpine.

Inside you'll find a well-appointed interior. BMW has you covered on all the bells and whistles: head-up display, rear view camera, park distance control, 3G network capability, full Merino leather and more. The Air Collar that blows hot air around your neck comes standard in the M4 Cabriolet (optional in the 435i Cabriolet). It's an incredibly useful feature when the temperature drops and the goosebumps start popping out. Combine that with the heated seats and the wind deflector, lo and behold you've got yourself an all-season cruiser.

Let's talk performance. Yes, the Cabriolet comes into the fight with a weight penalty but it still feels honed and concentrated. We've lost two cylinders in the transition from last generation's M3 to the M4 but in its place we've gained two turbos. What does that translate to? It means that maximum torque (406 lb-ft) is available from as low as 1,850 RPM and it doesn't let go of the rope until 5,500 RPM. This is an engine that is happiest being run hard.

Gone is the howling screech of eight cylinders but so is the abysmal fuel economy. The M4 falls short of replicating that exhilarating exhaust noise but it's gained rather decent fuel numbers. We averaged 13.2 L/100km with a mix of city and highway driving. Not bad for a car of this magnitude. A friend of mine who owns an E92 M3 says he averages around 15.5 L/100km even though he never travels above 5,000 RPM. Imagine your stratospheric gas bill if you were to actually push that M3 to its limits.

There are two transmissions to pick from: a 6-speed manual gearbox and a 7-speed double clutch transmission (DCT). To somebody who has never sat in an M car before, the DCT's gear shifter will take some getting used to because there's actually no park button. Rather, you leave it in drive, pull up the handbrake and shut off the car. If you leave it in neutral the car will remind you to stick in into gear to lock the car in place. It's a transmission that behaves on both sides of the manual/automatic spectrum.

No doubt that purists will flock over to the traditional 6-speed, but I personally love the DCT. There's a limit to how fast a human can shift no matter how dexterous or articulate we are with our limbs. Instant downshifts and rev-matches are effortless with a mere flick of the paddle. If you blink, you'll miss it. It's just so, so easy. Flick right to quiet it down, flick left if you want to hear some noise. You can also control the shifts on the center console via the M shifter - BMW designed it appropriately to mimic a clogged acne pore ready to explode. Probably from all that turbo boost.

The M4 Cabriolet doesn't feel as fast as the coupe variant and we attribute that to the added weight. Confidence is lacking in the corners and the M4 is hesitant to let the rear slip out. Even on the most comfortable settings, the M4's stiff racebred chassis comes at the expense of ride quality. It's not as composed as the Coupe but Cabriolet owners will sign that dotted line knowing this. They've already accepted the fact that the topless M4 is not the perfect performance car, nor is it the fastest in a straight line, but it certainly is one of the most enjoyable.