Slang indeed.
I'm going to be 60 and all the old guys that taught me are almost gone now.
They used "Kemp" and also "Short" when referring to a cool car.
I remember back in 1973 I was asked to go pick up the husband of a family friend. He was a older Vietnam vet who couldn't drive at that time. I picked him up in my 1956 Merc 2 dr hardtop with a tuck and roll interior.
He got in the car. Closed his eyes and smiled. He then said to me. "I haven't ridden in a sweet short like this for a long time." He is most likely close to 80 by now if he is still with us.
Torchie