The new 'D' versions feature an electric motor on each axle, whereas the existing line-up only has a driven rear axle. The addition of a driven front axle boosts traction and improves stability, consequently widening the car's appeal in markets where inclement weather and poor road conditions are frequent.
Customers will be able to pick from three variants – the 60D, 85D and P85D. UK pricing has yet to be announced, but the all-wheel-drive Teslas command a premium of $4000 – approximately £2500 – over rear-drive models.
That means that, in the UK, a four-wheel-drive Model S 60D would cost £57835. The flagship P85D will set you back around £76,635.
Tesla boss Elon Musk said: "What makes this unique and better than previous all-wheel-drive cars is that you can dynamically shift the power from front to rear at the millisecond level; you can very quickly adjust torque – more than is possible than with a mechanical system.
"With all all-wheel-drive systems out there, they're less efficient. In the case of the Model S, because we can shift the power so quickly, we can be constantly at the most efficient point for the individual motors and overcome the weigh penalty. Literally everything improves."
The 60D and 85D's electric motors produce 188bhp and 181lb ft, resulting in a combined 376bhp and 362lb ft. The 60D variant has a claimed top speed of 125mph, a 0-60mph time of 5.7sec and a range of 225 miles at an average of 65mph. The higher-performance 85D delivers 155mph, 5.2sec and 295 miles respectively.
What's most notable, however, is the new flagship version – badged the P85D. It packs significantly more powerful motors, with the front electric motor producing 221bhp and 244lb ft, the rear 470bhp and 443lb ft. That means a net output of 691bhp and 687lb ft.