Mystery Machine upgrade and its timeline reflections

Wow, judging from how the Mystery Machine has evolved, these 'meddling kids (and a mutt)' doesn't seem to age at all.
As we know, the original Mystery Machine was a Volkswagen Kombi Wesfalia of early 70's, with front-mounted spare tire. Fred's scarf confirmed the style of the era, beside the fact that the car was also a culture hype / trend of its time.
Now in this movie, Fred restored the Mystery Machine by using a recently built van of the time, which as we can see is a Chrysler Caravan of early 90's.
20 YEARS OF GAP! Would you believe that??