KEY POINTS:
Five-year-old Calem, is a friend of my daughter's. His dad drives an E36 BMW M3, which makes Calem a young man with an unhealthy M-car obsession and unnaturally detailed product knowledge for one so young.
Calem is nestled in the back of my M6 convertible test car and naturally, he wants to know just how fast Munich's ultimate M-machine is.
I dial up the full 373kW from the V10 engine via the iDrive controller (the M6 is limited to a paltry 298kW at startup), select the most aggressive of seven separate settings for the robotised-clutch sequential manual gearbox (SMG) and give the throttle a hard stab through to 50km/h. It goes by in a flash, the wailing M-Power motor only just getting into stride.
"How was that?" I ask. "Fast," replies Calem. Then, thoughtfully, he says: "In fact, I'm a little bit scared."
You should be, young man. The M6 convertible is BMW's fastest-ever drop-top - it rockets from 0-100km/h in 4.8 seconds and can cover a standing kilometre in just 22.9 seconds.
It's also the most expensive M-car you buy, at $270,900. That's $15,000 more than the M6 coupe and a whopping $45,000 more than the M5 sedan, which has the same basic powertrain and chassis.
No doubt there will be people who will buy the M6 convertible simply because it's the most costly 6-series available. But it's not an easy car to drive - BMW M-cars, even big, posh, open-top ones, are highly focused machines and not well suited to cruising city streets.
The throroughbred engine is grumpy when cold and the seven-speed SMG transmission requires time and your full attention to operate smoothly, even with a range of different shift-speeds to choose from.
This M6 may have a soft-top, but you'd never call it a soft proposition. It's as painstakingly engineered as any other M-car, with snazzy bespoke 19-inch wheels and tyres, specially tuned suspension, massive brakes, a performance-oriented stability control system and the M-Differential lock to prevent rear-wheelspin without impeding acceleration in tight corners.
It's every bit as capable as you'd expect of a genuine supercar. It's electronically limited to 250km/h by the factory, but the 330km/h speedometer hints at the true performance potential.
Which means you really need to keep your eyes on the road. Luckily, the M6 has BMW's head-up display as standard. This clever system reflects vital information onto the windscreen so that it appears to be floating just ahead of the vehicle.
It's all very high-tech, but isn't a convertible supercar a bit pointless? In principle, yes. If you want the ultimate driving machine, best not to undermine the experience by choosing the version that weighs 220kg more (due to the extra body strengthening required) and is substantially less rigid.
Indeed, while the M6 drop-top is rock-solid in hard cornering, our test car betrayed its roofless status with incessant creaking from the A-pillars over speed humps and vehicle entrances.
Opting for the convertible also means you miss out on one of the coolest features of the M6 coupe - its unpainted carbon-fibre roof, which reduces weight and adds visual grunt.
On the plus side, folding away the lid does grant much greater access to the aural delights of that V10 engine, which does amazing things as it slices through the revcounter to 8000rpm.
If I was signing the cheque (yeah, right) I couldn't see the sense in the M6 convertible. But for a few days, it really was an experience not to missed.
