Yesterday, I went for a small drive in the Audi RS4 estate and thought, after a small while, that it may be the most complete car money can buy. It's fast, practical and not at all ostentatious.

But then I came home, gave the matter a bit of thought, and realised that actually, it's no more complete than an unfinished jigsaw. The front seats are so huge, there's almost no leg room in the back at all, and it is extremely expensive.

So then, this being a wet bank holiday Monday, I started to wonder if there really is such a thing as a complete car. We talk, often, about the world's fastest car, and the world's greenest car, and the world's most economical car. We bask in the magnificence of the Rolls-Royce's ride and we marvel at the extraordinary reliability of the Honda V-tech system - 15 million made and not a single warranty claim so far.

But is there a car that brings all of these things together, wraps them up in an easy-to-digest, value-for-money package and is sitting there on the shelves right now, waiting to be identified? Because if there is, you can forget the Phantom and the Veyron. It would have to be the greatest car in the world.

I'm talking about the automotive equivalent of someone who never existed: think of a person with the naval skills of Admiral Nelson, the writing prowess of Sebastian Faulks, the engineering pizzazz of Isambard Kingdom Brunel, the political brilliance of Nelson Mandela and the looks of Jim Morrison.

Of course, you may think it's impossible to combine, say, comfort and handling. You may argue the two things are mutually exclusive, and you may continue to argue this until you step into the new Audi R8 which will prove you wrong. Even without its magnetic suspension, it manages to handle and is so smooth you can run over a medium-sized man and not notice.

It's the same story with fuel economy and speed. You may say any car capable of blistering the skin off your face with its pace and panache will, by its very nature, gorge on fuel in the manner of a hot dog presented with a refreshing mountain beck. I don't even need to stray beyond Audi, again, to show you you're wrong. The A8 with the V8 diesel goes like a bastard but can, if you're careful, return in excess of 40mpg.

Sadly, however, the A8's claim to be a complete car stops at this point because the ride gives you some idea what it might be like to be washed through a crazy-golf course by a large flood.