When I was about seven years old, I not only went to a Wienermobile appearance and got a whistle, I met Little Oscar.
I saw it a couple times as a kid (60s) and once even with Little Oscar from the commercials. I have not seen it in person since maybe 1971 or so ------- just something else I always blamed on Nixon. 
I’ve seen the Wienermobile three times I think. Twice in the wild, once at a Kmart in San Jose and another time parked behind my hotel in Pensacola. I’ve also seen the one on display at the Henry Ford Museum.
I’ve seen it on the road once or twice, and parked a handful of times. It probably helps that I live in the Midwest, and went to school in Madison, WI (as Oscar Mayer is based there).
Yep, parked right outside the factory in Madison, WI.
From today’s Onion:
I’ve seen both the Weinermobile and the Planter’s Nutmobile in the parking lot at work in southern Oregon (the Weinermobile more than once). I have also seen the Goodyear Blimp up-close-and-personal.
I had a friend who drove one, and I was riding with him when he was pulled over for speeding. No ticket. This was about 23 years ago.
I worked with a guy who spent a summer driving the Weinermobile (one of them, anyway.) He said the experience was fun, but the Weinermobile was hot and stuffy and the engine tended to overheat.
I used to see it all the time when I was a kid in the late 40s. Not sure if I’ve seen one since.