It was a take-off by National Lampoon, on a commercial actually put on TV by Volkswagen. As such, it was one of the greatest spoofs of all time, due in no small part to its absolute truth.
In their "real"commercial, VW was trying to point out how well the doors fitted etc. on its cars, in contrast to the loose-fitting dors, creaky seals etc. of American cars. They showed a VW bug floating in water, maybe a swimming pool. And the narrator was saying, look, the VW is so well put together, it barely leaks any water, boy that is good body construction etc. It was an OK commercial. And well-remembered for the weird sight of a car floating in deep water.
Some time after that, Ted Kennedy ran for President and lost. Chappaquiddick was brought up, but mostly downplayed by the media which was almost as biased then as it is now.
Then National Lampoon came out with that print ad, which looked amazingly like the commercial for obvious reasons. The circulation of the magazine tripled overnight.
It was one of the greatest ads I've ever seen. Even if it was a spoof.