The late novelist John Le Carré once said, “A desk is a dangerous place from which to view the world.” As it turns out, what was good advice for spies is equally good for manufacturing and design engineers.

DETROIT—Engineers behind the Chevrolet Corvette, Cadillac CTS, GMC Sierra and Buick Enclave are learning on dealership sales floors and in service bays what customers like and dislike about the cars and trucks they helped create.