Very cool car, I've often wondered what it was. Perhaps a custom job.
Here's what imdb.com says: The fancy finned-back car driven by the Kerbys was custom built by the Bohman & Schwartz Co. using a 1936 Buick Roadmaster chassis. Originally the producers had in mind to use a coffin-nosed Cord, but it wasn't large enough. In the custom-made Buick there were special compartments for camera equipment, etc. The Buick resembles a Cord, but the supercharger pipes on the side were just decorations (a Cord comes with an actual supercharger). After filming the Buick was bought by the Gilmore Oil Co. and was used for promotional purposes for many years. It was updated in 1954 with a Chrysler Imperial chassis and drive train. The car driven by Cosmo Topper is a 1936 Lincoln Model K.
Anyway, your guote got me to thinking about Indian dialogue. How about Burt Lancaster in "Apache."
Assuming I'm right, try this:
"I wouldn't give you the skin off a grape."