And it said it'll have a hopped-up version of its Model S that has all-wheel drive and blasts to 60 mph in little more than 3 seconds.

Tesla's moves are closely watched by its shareholders, who seem to bid up stock prices wildly, then sell, so the Tesla shares rocket, then tumble, somewhat like technology stocks. And the electric-carmaker's moves are considered a foretaste of what mainstream automakers might need to emulate to stay abreast of the latest technology.

Tesla announced Thursday that the all-wheel-drive versions of its Model S electric car will manage a slight increase in range of about 10 miles on a charge vs. the rear-drive models — for a maximum of 275 miles — because of efficiencies designed into the new system.

The AWD cars have a second electric motor to drive the front wheels. AWD hybrids, such as the Lexus RX, likewise use separate electric motors front and rear to accomplish all-wheel drive. That eliminates the need for a front-to-rear driveshaft and other cumbersome hardware.

CEO Elon Musk called his system "a huge improvement" that he claims is "taking the technology to the next level."

The AWD cars will carry the designation D, and the new top version of the Model S, the AWD P85D, will be among the fastest-accelerating sedans ever: 0-60 mph in 3.2 seconds, according to Tesla. Five or six seconds is considered very quick.

The 85D models start being delivered to buyers in December. The other AWD models, 60D and 85D, arrive in buyers hands in February.

The addition of all-wheel drive will allow Tesla to compete more vigorously in the snowy East and Midwest, broadening is buyer base beyond the Sunbelt.

Jaguar made a similar move to AWD in 2013, figuring it was competing in a shrinking minority of the luxury market without AWD.

Tesla's suite of safety features and driver aids is partly catch-up, partly leapfrog.

Brands from Mercedes-Benz and Infiniti to more mainstream nameplates such as Hyundai have features that will keep a car in its lane, steer it back if it begins to wander, stop without driver help if it's racing too fast toward the car ahead.

But Tesla CEO Elon Musk says Tesla is adding innovations to those.

Two highlights:

•The new system will move the car over a lane when the driver uses the turn signal.

•The car reads speed-limit signs and adjusts the car to the speed on the sign.

Other features match the lane-departure warnings and other safety and driver-help features that are getting common.

Tesla says the cars it's building now have 12 sensors each able to "see" 16 feet to enable the safety tech. Those can't be retrofitted to older models, Tesla says.