Here are the three new choices:
*The baseline model will be a single-motor Model S 70 that will have a lower starting price of $70,000, versus $75,000 that the company announced in April this year when it increased the car's battery pack from 60kwh to 70 kwh and made the car all-wheel drive with dual motors
*For $10,000, a Model S owner can add the "Ludicrous mode" that boosts the acceleration of 0 to 60 mph to 2.8 seconds from 3.2 seconds.
*The largest battery pack now comes in 90kwh instead of 85kwh. That should increase the range by 5%, or around 13 miles. The upgrade costs $3,000.
The energy density improvement is possible without the need to increase the physical size of the battery pack. That's because the lithium-ion battery cells now uses silicon for part of its anode, Musk said. Lithium-ion battery cells typically use graphite for anode. Lots of research has looked into the benefit of using silicon for the anode because silicon can hold a lot more lithium ions. But it also can expand so much that it fractures and becomes unstable. Tesla uses Panasonic's lithium-ion cells.
"It's a baby step in the direction of using silicon in the anode," Musk said during a press conference call. "But we will increasing the use of silicon in the anode.
Improving the battery technology — in energy density, weight, performance management and price — is crucial not just for Tesla's survival but also the consumer acceptance of electric cars. That 90kwh pack is important not just for attracting buyers to Model S, it also will reduce the impact of the heavier Model X on the driving range.
Model X, the SUV that is due for launch this year, will be about 10% more mass than Model S, and that means it also will use that much more energy per mile, Musk said. The 90kwh pack is a 5% improvement in energy density, so it would lessen the range losses for Model X.
"The 90kwh pack is an important element for the X," Musk said.
Overall, Tesla plans to increase the battery range 5-10% every two years, Musk said. The improved battery packs would be available in new cars and as upgrades for existing vehicles. Musk said he wouldn't recommend an upgrade every time a new pack comes out because it might not make financial sense.
"I wouldn't recommend that people upgrade every year unless they are on the edge of the range," Musk said. An upgrade every 3-4 years should suffice, he said.
