Silicon Valley upgrades the Porsche 911

Silicon Valley has beaten Porsche to the draw and launched its own version of a 911 hybrid, says Kyle Fortune in Car magazine. The Santa Clara-based firm Vonnen has worked out how to "pancake an electric motor between the engine and gearbox" to create a hybrid engine and has named its technology the "Shadow Drive". The electric motor adds up to 148bhp of power that increase alone is more than the total power of a 911 engine from 1973 while adding only around 77kg to the total weight.

It doesn't come cheap, however. The Shadow Drive system costs £57,705 to install. That's more than 60% of the £93,110 starting price for the original Carrera. That makes the hybrid adaptation an exclusive proposition. It takes the total cost to more than £150,000, and you get a less practical car into the bargain the position of the electric motor system in the back of the car means "you will have to forgo the small amount of luggage space" that other 911 drivers enjoy, says Michael Bath on Drive Tribe.

But it will turn your modest Carrera into something significantly quicker, says Fortune. The additional motor is "seamlessly integrated", and makes the acceleration feel "vivid, oddly reminiscent of a pure electric car in its surge, but piggybacking that of a standard 911 to create a supremely well integrated whole". Vonnen reckons the hybrid drive can, with a bit of tweaking, be fitted to any 911 right back to 1965. Boxsters and Caymans, too. This hybrid is "enjoyable rather than earnest" more about speed than saving the planet but you needn't tell your green-leaning friends that when you boast that you have gone electric.

Price: £93,110 (starting price for the Carrera);£150,815 (with Vonnen Shadow Drive);Power: 500bhp;Top speed: n/a (official performance figuresnot yet released);0-60mph: 3.6 seconds (estimated)