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For this year’s version of the M4 BMW ditched the V-8 engine for an inline-six with twin turbochargers.

Over a light lunch at the Maisach BMW Driving Academy, Florian Staiger, project engineer for BMW's latest M3 and M4 cars, counts on his fingers. "Our customers told us they wanted three things for the new M series: for the car to be lighter, have better fuel economy and, lastly, for it to be meaner."

Staiger was involved in the project more than just at the drawing board; as a certified performance driver and trainer, he was also behind the wheel of the new cars in the testing stages. Today, he is trying to teach us the finer points of driving and drifting at this former Second World War airfield before we set out in the Bavarian alps with his new M4 convertibles.

Did Staiger and his team accomplish what BMW M enthusiasts wanted? Let's review.

With the fifth generation of the iconic M3 sedan and what used to be called the M3 Coupe and Convertible – now known as the M4 Coupe and Convertible – the German company used more aluminum and carbon fibre-reinforced plastic; this latest M4 Convertible is about 60 kilograms lighter than its predecessor, despite being slightly larger. So, check. Which, of course, contributes to its improved fuel economy numbers. Check again.

But the big change isn't just the weight savings. Where the previous car had a 4.0-litre V-8, BMW has gone back to its roots with an inline-six, this time with twin turbochargers.

What that means is a bump of 11 horsepower to 431, but more astoundingly, an increase of 110 lb-ft more torque to 405. It's the same engine shared by the M3 and M4 Coupe, though the added weight means it's a tick slower to 100 km/h at 4.4 seconds – no, not exactly dawdling. Despite a satisfying "brat" coming from the tail pipe, however, BMW felt it had to manufacture a more V-8 engine sound through the car's speakers.

But there's no need for shame. The engine's roar is thrilling with the top down, and it was too alluring not to shift down to second gear and punch the throttle in the mountain tunnels for that sharp, mechanical boom reverberating out back. But if the sound is exciting, the acceleration is rip-roaring, allowing for breathtaking passes of slower cars simply so we could enjoy more of the twisty mountain passes at speed.

It's not absolutely perfect; though it has sharp steering and handling, it does feel heavy sometimes. But is the new M4 Convertible meaner than its predecessor? Most certainly, check. And in this luxury performance segment, that's the most important point.

Tech Specs

2015 BMW M4

Base price: $84,500

Engine: 3.0-litre twin-turbocharged inline six cylinder

Transmission: Seven-speed DSG; six-speed manual

Fuel economy (litres/100 km): 12.4 city; 7.2 highway (figures based on EU cycle)

Alternatives: Audi RS5 Cabriolet, Mercedes-Benz SLK55 AMG

You'll like this car if: You like to apply sunblock before donning your driving gloves.

Ratings

Looks: The front and rear are a little busy, but the side profile is sharper and cleaner than the previous M3 convertible.

Interior: All the comfort and luxury you'd expect from BMW, though I don't like its small knobs for the radio and climate systems.

Performance: Smooth, linear power from the new inline-six, with sharp steering and a well-performing active differential. Still feels heavy.

Technology: Though the electronic differential is a pretty trick, the roof mechanism is the same as the previous-generation M3 Convertible.

Cargo: You're not going to carry much with the roof folded in the trunk.

The Verdict

8.0: It almost has the performance of the M4 Coupe, but the drop top means you can enjoy the surroundings and engine noise even more.

If you have questions about driving or car maintenance, please contact our experts at globedrive@globeandmail.com.

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