Mercedes-Benz's S-Class V12 S600 Ubermensch model is the one that looks as if the cast of a science fiction movie invaded an Ulm industrial design studio and said: 'Do me a limo.'
But it has a problem. When you drive it, they think you are a chauffeur. That's no bargain for pounds 100,000. I took one to lunch at The Connaught Hotel to meet an old friend, a New York car nut - originator of the Rallye de Grappa, the alcohol-fuelled run through the Veneto and Slovenia. There I was in my bespoke suit, good shoes, expensive haircut, mortgageable watch, and the guy at the door, instead of offering to park it for me, assumed I was the driver. With some cars, you want a window sticker saying: 'Don't blame me, it's only on loan.' With a big S-Class you want it to say: 'Excuse me, honest, this really is my car.' The day after, I drove it in torn jeans and T-shirt and felt better.
And there's another problem. The S-Class has a completely gorblimey electronic security system. This, I promise, is amazing. It comprises a plastic thingy the size of a credit card. As you approach the parked vehicle with it, it opens for you. Inside, no proletarian keys for the Ubermenschen: you just put your hand on top of what used to be called a gear lever and the mighty motor flutters into powerful life, with only a nervous pulse through the pineal gland to let you know it's happening. Journey's end, you get out of the car and, at a sensible distance, it locks itself.
Amazing - and it works. The only fault is one the technicians isolated in Stuttgart Unterturkheim never thought through: you get so used to this automated facility that the real world feels deficient. You start bumping into resolutely locked wooden doors expecting them, too, to be supplicants to electronic control.
The Bentley Azure is a complete contrast. This is where new money meets old technology.While the coruscatingly technical S-Class Merc is the favourite vessel of people whose position in life brings with it a man in uniform, the archaic Bentley is the sort of thing you keep for ever and drive yourself.
The Azure is a living antique, not a transport system. And at a quarter of a million it is priced accordingly. Still, while the creaking, aristocratic Bentley makes the tight, shiny, modern Merc look plebeian, the two have a lot in common: these are the most extreme four-seater cars you can buy.
This is what great power and wealth look like when they take the form of automobiles. So, you'll want to know what you are missing.
Despite its size, the S600 handles with astonishing agility. The daunting momentum generated by gobs of power pushing enormous mass are controlled by intelligent systems that monitor every dynamic parameter: positive and negative acceleration, roll, pitch, yaw and - for all I know - re-entry into the Earth's atmosphere are all understood and compensated for.
It is simply impossible to get out of shape or feel uncomfortable in this car. Instead, you travel in absolute stability and silence on a tsunami of traffic-separating authority. The S-Class makes you feel special, although I personally found the ventilated massaging seats less of a rich man's plaything than I'd hoped.
In contrast, you ease the Bentley away from the kerb rather as you take a trawler out of dock. Manoeuvre cautiously. Not just on account of the fiscal responsibility entailed by inserting pounds 250,000-worth into the indecorous urban metal scrum, but because it demands a sort of genteel gravitas.
Being handmade, the Azure has a sense of approximation in its fabric: superb materials are all on chattering terms with each other, as are the eclectic components (cigar lighter: 'Made in Germany') that make up this unique vehicle. If it creaks, it is only in the same way that a country house whispers and moans at night. The Merc, on the other hand, has the integral feel of a Siemens phone.
Which you prefer is a matter of taste, not of wallet. Viewed uncharitably, it must be said you can look a bit like an exceptionally prosperous drug dealer in the Azure. But at least you don't look like the chauffeur. Why have an old Bentley when you can have a new Mercedes, ask the technocrats snootily?
The answer is, most people with a Bentley have a Mercedes as well, much as they also have a lawnmower. No matter how rich you are, there is no end to one-upmanship.