Lexus LC 500
Price £76,595
0-62mph 4.7 seconds
Top speed 155mph
MPG 24.6
CO2 263g/km

Ever since Alan Partridge proudly confessed, in a haze of Lynx deodorant, that he drove a “Japanese Mercedes”, Lexus has been keen to distance itself from the land of golfing slacks and risqué jokes. And no car has helped its cause more than its latest model – the LC 500.

It’s a futuristic-looking coupé which oozes road swagger. But the car also gave me my very own Alan Partridge moment… Having fired up the thunderous 5-litre V8 engine I drove off without realising I’d left the key on the roof. Two hours later I had the surreal realisation I’d managed to lose the key mid-drive. How can that be possible? I could have gone into a rant about the essential pointlessness of a proximity key and how you never know where to put it once you have started the engine. Instead, I spent a sweat-drenched two hours retracing my steps, knowing that if I stalled the car I’d not be able to restart it. I got lucky and found the key on the ground near where I’d first started the car. I then turned around and set off again – a two-hour trip becoming a six-hour fret-fest. Alan would have been proud.

Of course, this was my own dopey fault, but surely it’s something that could be averted. How about a message flashing up on the dashboard, saying: “Key, dum-dum!”?

Right, where were we? Oh yes, the LC 500… It is devilishly handsome. Few cars I’ve driven have made such an impact on pedestrians. Arriving at a red light triggers a Mexican wave of near hysteria; driving on the open road sends others zigzagging around you like dolphins in front of a tourist boat as they try to get a better look. The model I drove was gunmetal grey and its arrangement of scoops, inlets and mighty wings made it look like a suit of armour waiting to be animated by some giant force.

There are two engine options available: a whisper-quiet hybrid V6 and an old-school naturally aspirated V8 with the crowd-pleasing roar of a stadium rock band. I drove the latter and was torn between a feeling of old-world thrills and new-world anxiety. It ticks every box on the guilty-pleasure catalogue – it’s the foie gras of motoring, and the engine is quite astonishingly tasty. Downshift and the V8 sends a huge crack of lightning to the exhausts. But it’s also surprisingly biddable. You can drive it slowly.

The interior is an homage to the art of upholstering. It’s exact and precise with a lovely combination of smooth plastics and textured leathers. You’ll find two perch seats behind the front thrones – it’s a 2 + 2. And the boot is bigger than you might expect. It’s wonderfully comfortable to sit in, with the display and controls laid out around you like the keys on a futuristic organ. This is a car where you’ll never ask “Are we there yet?” You want the journey to go on and on…

Is there a but? Yes, there always is. The satnav is utterly, incomprehensibly useless and the touchpad impossible to use. I found myself navigating using my phone, which seemed crazy in a £76,000 car. Maybe it was me being stupid again, or maybe Lexus hasn’t quite shaken off its inner Partridge.

Email Martin at martin.love@observer.co.uk or follow him on Twitter @MartinLove166