interval shots look too choppy for speeding up driving videos.
your battery will die long before you fill up a 16 gig card, i went with a 32gig card, they aren't too expensive these days (less than half as much as a 512mb card back when i started digital) make sure you get a class 10 card, every SD card has a number with a circle around it (4, 6, 10) its the speed of a card. I had an older card that did not work so well in my camera, the video would stutter and drop frames because the transfer speed of the card was too slow. a 32 gig class 10 card from amazon is only 42 bucks.
i think the gopro will shoot about an hour +/- before the battery goes out. i would guess that drive took about an half hour.