Porsche 911 Carrera

The new 911 offers an excitement that belies its seven-gear direct fuel-injected efficiency

Time was when a fuel consumption of 30mpg was thought pretty good. That was when 70 profile tyres were the height of sportiness and the five-speed gearbox was starting to register on the radar of drivers who might not necessarily own a pair of stringback driving gloves. If your car did 30mpg, you were a prudent sort.

Today, it is different. There's a significant road taxation increase beyond 225g/km of CO2 output, which equates to just under 30mpg for a petrol car. So 30mpg is merely borderline acceptable and a car whose official "combined" fuel thirst is greater is deemed a gas-guzzler. In London it would have been even more significant had the congestion charge hike to £25 a day over 225g gone ahead. With the mayoral change, this idea has been shelved, which means that Porsche has withdrawn its legal action to fight it. So there's an irony to the fact that the subject of this test is not only a glamorous semi-supercar of huge power and speed, but is also the first Porsche 911 since cars were carbon-rated in 2001 that would have avoided that £25 charge. Yes, here is a 911 capable, officially, to average 225g/km of CO2 and just under 30mpg.

SPECIFICATIONS

Model: Porsche 911 Carrera

Price: from £63,070. On sale now

Engine: 3,614cc, flat-six cylinders, 24 valves, 345bhp at 6,500rpm, 288lb ft at 4,400rpm

Transmission: six-speed gearbox (seven-speed PDK optional), rear engine, rear-wheel drive

Performance: 180mph, 0-62 in 4.9sec, 29.4mpg official average, CO2225g/km

You can identify this latest incarnation of the 911's 45-year-old bloodline by the rather garish daytime running lights below the headlights – a string of light-emitting diodes seeking to make a style virtue out of planned EU legislation. It is under the rear-mounted engine's cover, though, that the real changes are found.

Direct fuel injection (DI), that's the key. It's the way to make petrol engines more efficient, partly because squirting the fuel directly above the piston has the effect of cooling the intake air as it is compressed. That means it can be compressed more without prematurely igniting, and this higher compression releases more energy from the fuel when it is ignited. But instead of making a DI conversion of its existing flat-six engine, Porsche has redesigned the engine completely. It now weighs less, has fewer moving parts, and it has more power. The standard 3.6-litre Carrera engine now produces 345bhp instead of 325, while the 3.8-litre in the Carrera S makes 385bhp instead of 355.

So, with conscience lightly greened, we try it out. The 911 in which I am installed has gear shift buttons on the steering wheel, an automatic transmission selector lever on the centre console and no clutch pedal. Formerly this would have signified a Tiptronic transmission, a conventional automatic. I have never liked the Tiptronic because it deprived the driver of intimacy. Now, though, it has gone and in comes the Porsche Doppelkupplungsgetriebe (PDK) which translates as double-clutch gearbox.

So what's new? Isn't everyone doing these? That's true, but the idea is actually a decades-old Porsche invention. It has just taken a while to get it to work well on the road. This gearbox has seven forward gears. It snicks up and down quickly, either automatically, with intelligence, or manually by means of the central lever or double buttons on the steering wheel. These you push forward with a thumb to change up, pull back with a finger to change down. Confusion is rife. What you should order, though, is the Sports Chrono Package Plus (SCPP). This gives a built-in stopwatch but also, more importantly, Sport and Sport Plus buttons. Press these to sharpen the throttle response, loosen the stability systems and, in a PDK car, speed up the gear change; Sport Plus can be near- violent in the speed of its gearshifts and it incorporates a "launch control" for fastest possible acceleration. The package also includes adaptive dampers.

For all PDK's cleverness, though, the manual gearshift is more satisfying. The new engine is smoother and quieter than ever, but it still has the right flat-six exhaust note when roused. The steering and handling are easier to understand, but you're still aware of the weight over the tail and the slingshot bend-exits it gives. This is a sanitised 911 for the modern world, but it's still a compact, practical, usable 911. Such low road tax, too ...

THE RIVALS

Aston Martin V8 Vantage: £83,000

Now with a more muscular, 420bhp engine, the Aston goes as well as it looks. A beautiful object, a rousing drive and a technofest of bonded aluminium construction.

Audi R8: £78,300

Surprising car for Audi to make, but this all-aluminium, mid-engined V8 machine with 4.2 litres, 420bhp and four-wheel drive is civilised and scintillating. Best as a manual.

Nissan GT-R: £52,900

Amazingly cheap for the searing pace and technology it offers, the GT-R has a 3.8-litre, twin-turbo, 480bhp V6, four-wheel drive, a sequential transmission and a giant cult following.