I appreciate the comments guys, but I based the JATO rocket on the picture below for size and general look. Although my illustration is a cartoon image … I like to incorporate some sense of realism in most of my work. It’s a “believable absurdity” I suppose.
I was going to make the rocket resemble a cruise missle at one point (so I guess on that level I agree with you). However, I changed my mind because it didn’t accurately reflect the story upon which this illustration is based.
The rocket will become a more predominant part of the image when I get to coloring it. There will be a noticable amount of flare coming from the back of the car that should challenge my weak lighting skills.
As for the flight issue … I guess the story is as much a part of my entry as the art. Although the “pilot” of the Impala had no intention of building this thing for flight, the JATO was obviously designed for this purpose. 
Oh … and for those who are interested, another rocket car story to amuse you.