What is it? Alpina's super-fast, super-luxurious and super-exclusive take on the BMW 5 Series.
The company starts with the 550i V8 petrol as a basis, swaps the two factory turbochargers for Alpina versions, fits different suspension, and retunes the electrically adjustable shock absorbers and eight-speed automatic gearbox. It also fits some discreet spoilers and some not-so-discreet 20-inch alloy wheels.
What's it like to drive? Comfortable and relaxing. That's right, this is a 500bhp estate that's capable of monstrous speeds, but it's the sheer serenity of the thing that makes the biggest impression.
Put the suspension into its softest setting and you'll waft along, largely unaware of the state of the road surface. Even the firmer settings don't ruin the ride, although Catseyes are felt and heard a little more than you'd like.
No matter what technical wizardry is happening beneath you, there's no disguising the fact that the B5 is a big, heavy car, though. It handles smartly for its size, but isn't particularly engaging, and feels happiest on long, open stretches of road.
That way you can indulge in the effortless thrust of the engine and the slick changes from the auto gearbox. At any revs and in any gear, performance is colossal.
Those huge tyres kick up some noise on rough surfaces and you can hear wind noise at speed, but it's far from intrusive and doesn't stop the B5 being a fine cruiser.
Not that you'll go far before having to stop for fuel. Expect 325 miles or so to be as far as you'll get. Then again, if a long range is top of your priorities, you'll be going for a diesel car.
What's it like inside? You can have the interior however you want it. Everything from the colour of the headlining to the finish of the hand-stitched steering wheel can be tailored to your requirements for a suitable price, of course.
The rest is standard 5 Series, which is no bad thing. The materials and build are first-rate, as is the amount of cabin space. The boot is a good size, if dwarfed by that of a Mercedes E-Class Estate.
Special mention must go to the standard Comfort seats. They support you in all the right places and are suitably cushioning to make long stints at the wheel something to be savoured.
Should I buy one? If you're in the market for an effortlessly quick, relaxing and practical car, then yes, the B5 is a good choice. You won't be able to use even a quarter of its ability on most UK roads, though, but it's nice to know it's there in reserve, should the need arise.
The big question, of course, is whether you should choose the Alpina over the new BMW M5, which is due in November. It'll have a 552bhp twin-turbo V8 and, at 73,040, will cost a fraction less. We'll be driving it in late September and you can read our first drive then. This time around, though, there'll be no Touring estate version.
Mercedes-Benz E63 AMG Estate
What Car? says