In 1952, the hot dog manufacturer patented the design for the iconic Wienermobile, but other versions had already been around for a while. The Wienermobile actually built off a 1936 design that was even more streamlined. Though the 1952 patent is credited to Mayer, other sources credit industrial designer Brooks Stevens as being behind the great automotive breakthrough.
The Wienermobile is probably a big reason we identify the company with hot dogs, along with the iconic 1965 "I wish I were an Oscar Mayer wiener" jingle. When Oscar Mayer founded the company in 1883, it was a meat-packing business that sold a range of products, including non-sausage stuff like corned beef. Only over time did its brand identity as a wiener-producing juggernaut emerge.
You can see the rest of the patent illustrations below. Though the design of the Wienermobile has changed since, the 1952 patent shows that the big epiphany was always there: a giant hot dog stuck on top of a car:
The full illustrations for the Wienermobile patent