Re-reading this post from the beginning and following the links to articles where Elon speaks about the next-gen Roadster there are a couple indisputable facts:
(1)
Model R will be 2+2 seating - Elon owns a Porsche 911 Turbo and wants the rear seats. They will be tiny, no doubt, but they will be there and therefore it is not a true "Roadster" according to the definition, which is why I'm calling it the Model R.
(2)
Model R will be AWD - Tesla has said over and over that the Model S would be faster if they could drive all 4 wheels instead of the back 2. The Model R will be AWD so that it can be wicked-fast.
(3)
Model R wil be based on Bluestar skateboard - It will use Bluestar battery packs and that will necessitate Bluestar dimensions. So a foot shorter than the Model S (104" wheelbase) and a half foot narrower (<60" track). Current Roadster has a track of 58.7" and wheelbase of 95.1" (pick up 9" for the rear seat).
There are a couple other things that I would not label as facts but strongly suspect:
(1) Elon wants it to be the fastest production car in the world from 0-60. So faster than Nissan GT-R, faster than Porsche 911 Turbo S and possibly faster than Bugatti Veyron.
(2) I suspect it will be easy for a 6'5" person to get into and out of and drive. I doubt Franz Holzhausen is going to design something he can't fit into.
(3) It will be much more luxurious because Tesla will find it easier to make it so and it will appeal to more people.
(4) Bluestar is not coming before 2015 so it's doubtful that the Model R will be released before then.
(5) Given the battery pack size relative to size and weight of the car it will have 400+ miles of range (see below)
Final note:
I'm not smart enough to check his math but stopcrazypp
Next gen Roadster says the Model R would need a 110 kWh battery (590 hp) to be fastest. With the 4.0 Ah batteries (which dsm363 pointed out will be available in 2013) which have roughly 30% more power than today's 3.1 Ah cells in the 85 kWh pack, but 20% less space in which to fit, it seems like you could get to 85 * .80 * 1.3 = 88 kWh. So the question becomes how do you bridge the gap?
(1) Tesla could add extra batteries in the front and rear trunks (seems highly unlikely).
(2) Perhaps Panasonic comes out with 5.0 Ah cells by 2015 (seems very challenging).
(3) Perhaps there are advances in UltraCapacitors allowing power delivery at greater than 440 kW. These UltraCapacitors would serve as buffers between the car and the battery, helping to maximize battery life and performance at the same time. (don't know if this technologically feasible).
(4) Perhaps they can slash the weight on the Model R to about 3,000 pounds in which case 470 hp might be enough to win the race. (seems the most straightforward).
