Now, in a right-hand-drive car the ideal accessory at this point is a passenger pre-armed with a credit card but, if you're travelling alone, the toll booth is a pain, forcing you to park at the barrier and walk round to the unsmiling cashier.

However, thanks to a top tip from French evo reader William Parton, the 645 now sports a 'telebadge' in its windscreen. This little grey box allows you to enter the 'telep΃©age' lane, where the barrier rises automatically for you to sail through without stopping. It's heaven to use.

You can get one from the telep΃©age offices located at the bigger p΃©ages (details at www.sanef.com); show your passport, fill in a form and choose whether you want to pay an annual 20 Euro fee or a two Euro fee for each month you use the French Autoroute. Then hand over your credit card and in return for a 30 Euro returnable deposit, you'll get the coveted telebadge. Billing for any journeys you make goes straight onto your credit card.

After calmly blatting across France for most of the day, joining the Italian autostrada in the early evening rush comes as a bit of a shock. Soon I'm tagging along with a group of autostrada 'pros', haunting the outside lane with seemingly little regard to the national speed limit. There's no getting away from it, the Gadgetron plays this GT role to perfection, utterly unstressed at the 120mph cruise we're maintaining, the sports seats superbly comfortable over long distances, the suspension unfazed by the unpredictable quality of Italian tarmac. The clever anti-roll system works unobtrusively too, killing any unnerving body lean through the fast sweepers the Italian motorway builders are so fond of. Meanwhile, the big V8 gently hums to itself just below the 'snarly' zone, with seemingly plenty in reserve.

Just how much is in reserve I find out later on a German autobahn on the way home, when the 6-series powers through the supposed 155mph electronic limit before going beyond the final 160mph marker on the speedo and sinking well into no-man's land between the end of the speedo and the start of the fuel gauge. Naturally, I won't be taking it back to the dealer to complain that the speed limiter is faulty.

It isn't all plain sailing on the way down to Tuscany, though, as a number of annoying faults appear. Firstly, the sat-nav doesn't like you switching off the engine (say, to refuel) before you reach your destination. Absolutely nothing remains in the memory, forcing you to input all the details again. Another surprise was that the climate control can't cope with the Italian summer and the only way to keep cool in the 30-degree heat is to hit the 'Max' button. And unloading the boot in the dark is tricky thanks to the absence of a boot light - our car just has a loose wire poking out of a hole in the boot-roof, indicating that there probably should be one.

Over the next couple of weeks the twists and turns of sinuous Italian roads brought home just what fun a big, front-engined, rear-drive coupe can be. First, though, you have to switch off the ridiculously cautious traction control by holding the button down for 5sec to disengage it completely; the wait was definitely worth it on roads like these.

It probably helped that the last few miles to our Italian house is a 'via blanca', or white gravel road, which doubles as a local rally stage. I don't know if BMW has ever considered going rallying again but the 'Six' would seem a good place to start if my holiday experience is anything to go by. It's worth noting that at night the optional steering-linked swivelling headlights are worth several seconds on the blast home. Just a thought.