Road Test: Porsche Panamera 3.0 V6 S E-Hybrid 4dr Tiptronic S

As pretty as the Porsche Panamera Sport Turismo is to look at, its styling is not the only story here. It's the new plug-in hybrid electric drivetrain which the sleek new silhouette is hiding that's the main feature. It's entirely possible, if you believe the swirling rumours, that a production version of the car will be built in a few years, but for now you really shouldn't let that knowledge affect your buying decisions.

The e-hybrid drivetrain, as Porsche calls it, will debut much sooner. Effectively a thorough upgrade of the existing Porsche parallel hybrid drivetrain found in the current Panamera and Cayenne, e-hybrid swaps the existing nickel-hydride battery for a much more perky lithium-ion unit.

This is almost exactly the same size as the more ploddy ni-hy cell but offers much greater storage capacity. The li-ion battery offers more of everything you want from a hybrid - faster acceleration, greater range and a higher top speed without having to resort to waking up the 333bhp, 3.0-litre V6 supercharged petrol engine, a carry-over from the current system.

The other new element - besides the ability to plug the car into the mains - is the electric motor, which now produces around double the amount of power (95bhp) compared with today's electric engine. This brings the total drivetrain output to a maximum of 416bhp, allows a top all-electric speed (if you feather the right pedal) of over 81mph and increases the maximum all-electric range (not at 81mph, I might add) to about 18 miles. Petrol consumption is a claimed 81mpg.

If you just get in the car and start driving, it defaults to all-electric driving as much as possible. This can be overridden by slamming down the throttle, or, more elegantly, by pressing a wheel-mounted button. This allows you to charge up the battery as you zip down the motorway and then cruise into town on a wave of electric silence. Charging using an AC plug takes two and a half hours.

In the Sport Turismo, the system worked perfectly, cutting the engine on cue and bringing it back into the game as soon as asked. It also demonstrated in bursts of vivid acceleration down a sleepy section of Sunset Boulevard with a police escort, that it is still very much a Porsche. Its 0-62mph time is quoted at about six seconds, but it feels faster than that.

When fitted to a production Panamera, the sensation will undoubtedly be more muted, but still a significant advance over the current car. It's a pity that Porsche won't do the same for the styling, but with the Panamera Sport Turismo breaking cover, there's hope even that will change for the better soon.