In eight years, automobiles haven't really changed much. Essentially, the only thing that has changed in the past fifty
years is the piling up of electronic trinkets; if a war or a border shape were to depend on automobiles, then one from the sixties would be identical to one from today.
Why should technology change rapidly in the TNG universe? The Federation is a couple of centuries old already, and unlikely to be in lots of internal turmoil any more, so that wouldn't be a driving force for exceptional innovation. Most of the member species were old and established even when joining; would there be anything left to invent? Apparently, there's no market for anything, no profit from the introduction of novelties, so why invent anything new? The only incentives seem to be "for the heck of it" and "in response to an external threat"... And the threats haven't really evolved in the period we have witnessed. Save for the coming of the Borg, and that threat seems to be so far out of the league of our heroes that it's not producing anything.