if a 60 or 70 yr old with shakey hands (or too much coffee) can't operate the gui safely in a moving car, then the UI team failed.
not only are your fingers shakey (age, coffee, stress) but the road is bumpy and so you have 2 shakes going against you, possibly.
fine finger control on a touch screen is NOT what anyone considers a good thing for controlling thousands of pounds of moving metal and glass on wheels.
touch screens suck and its still in a proving period, before the masses have all been converted over to the knob-less style of UIs these days. but really guys, we're going in entirely the wrong direction here. if we're having trouble using this effectively, and we're the NERDS (so to speak), then what hope is there that joe average is gonna really like this?
fail. tesla, go back to school. and hire professionals. NOW, before you ruin another thing.