If you don't believe that power is the only thing that matters in a performance car, this is probably the best Porsche 911 you can buy. It uses the same engine (3.6 litres, 320bhp) and four-wheel drive transmission (between 5% and 40% of the power going to the front axle as required) as the regular Carrera 4, but the suspension, brakes, wheels and tyres are based on those used on the much more powerful 911 Turbo.Those brakes are pretty beefy, and the rear bodywork has had to be widened by 65mm, compared with the ordinary 4, to accommodate the 295/30x18 rubber. As a result the 4S is heavier, and therefore slightly slower, than the car from which it has been developed. Still, are we worried about the difference between 5.0s and 5.2s from 0-62mph? No, I thought we weren't.Our recent feature on the subject made it clear that if you drive a 4S and a Boxster S on a race circuit, all the fancy chassis work in the world can't overcome the fact that the 911's engine is in the wrong place.But road driving and track driving are two completely different things, and anyone who thinks they're not wouldn't be much use in a race. Take the 4S out into the real world and it behaves superbly. There is hardly a hint that the tail will swing out on you if you get it seriously wrong - what you're conscious of instead is an enormous amount of grip combined with the phenomenal stopping power of Porsche's Ceramic Composite Brake system.It's easy to feel invulnerable in a car which holds the road so well. Whether or not this is a good thing is a matter of debate, but it does make the 4S one of the most relaxing cars to drive of its type. The effect is enhanced by a very comfortable interior with leather all over the place, light controls (including a gearshift - this being a six-speed manual rather than a car with the £1960 Tiptronic option - whose quality makes that of many rivals seem ludicrous) and the electrically adjustable seats.Well, actually, I'm guessing about the seats. Those are the ones fitted as standard, but the test car had bucket-type seats with practically no padding and with no adjustment other than fore-and-aft. If you don't like the angle of the back, forget it and pick the standard seats instead.I can see the point about the bucket seats, which certainly hold you in place. But you have to be of the height which the designers had in mind. I'm taller than that, and I found my shoulders were pushed too far forward, which in turn caused a pain in the small of my back after very few miles.It's almost impossible to find any way of using the handling potential unless you take the car on to a race circuit, in which case I'd prefer the Boxster anyway. Likewise, you're not going to find many opportunities for using 320bhp. But at least there's an aural treat for you no matter where you're driving, since the thunderous flat-six engine sounds absolutely wonderful all the way from tickover to the red line.My pet theory about high-performance road cars is that they must be easy to drive slowly, since that's what they will be asked to do most of the time. So I spent ten minutes dawdling through traffic in a busy town and found that the 4S potters along without any fuss whatever.Full marks there. At the same time, I couldn't help noticing that despite the wide bodywork, which makes this car look decidedly butch even by 911 standards, it didn't seem to make much impression on anyone who saw it.I'm sure this wouldn't have happened with a "classic" model (pre-1990s, say, when the headlights stuck up above the swooping bonnet line and made every 911 look like a bullfrog which had just been asked a difficult question while shaving). There's no doubt that the current shape has a wonderful combination of elegance and brutishness, but it doesn't seem to stand out from the crowd the way the old one did. Engine 3596cc, 6 cylinders Power 320bhp Fuel/CO2 25.4mpg / 274g/km Acceleration 0-62mph: 5.2 seconds Top speed 174mph Price £62,260 Details correct at publication date