Or does the stress (á) make Camaro look so different from camarón that no one but me sees the similarity?
According to the Diccionario de la lengua española, camarón (shrimp) is the augmentative of cámaro, from the Latin cammărus (a sea-crab, lobster). Note that shrimp swim backward (not the best connotation for a car), but mantis shrimp are credited with "the swiftest kick, and perhaps most brutal attack, of any predator." As for the speed of lobsters:
Generally, lobsters move slowly by walking on the bottom. However, when they are in danger and have to flee, they can swim backwards quickly by curling and uncurling their abdomen. A speed of 5 metres/second has already been recorded.Five metres/second is about eleven miles per hour. Not very impressive.
I'm guessing the name of the car has no connection to those scuttling ragged claws of T.S. Eliot's objective correlative. Anyway, Eliot was already dead when the Camaro came out, so he didn't get to drive one.
And as for cockroaches, as Professor Joseph G. Kunkel explains, lobsters are called "roaches of the sea" for good reason. The next question would be "How fast are cockroaches?"