So I spoke with JB Straubel at the Model S event and asked him a few questions about ground clearance which led on to the use of air suspension and active ride height. I call it active ride height as I am more used to hearing that term in Formula 1 racing where it was used for many years (before it was banned in 2010 to slow down the cars). JB basically described a system (air suspension) where the car adjusts automatically to car speed and road conditions and decreases/increases ground clearance as a way of improving efficiency and adjusting downforce, which will in turn improve handling even more. The system is smart enough to ignore intermittent roll (e.g. from cornering) and to only adjust appropriately. If the driver doesn't want to engage this (someone had mentioned a worry on another thread about ground clearance in northern winters) he/she can control the ride height manually from the touchscreen. This manual control also allows the driver to "lower" the car for unloading the trunk. Although Tesla is still deciding some of this stuff, it is my distinct impression that the Sig series will have this as standard and it will be an option for all others. I know there's a lot of interest and some of the rest of you will also have picked up info, so I created a new thread. BTW, JB also told me that in testing the Beta's had been easily exceeding 300 miles (guessing that's where the 320 number comes in). Final BTW, He's a very bright guy for someone who looks young enough to be my son!