The car, Interceptor, is unlocked after the Deliverator. In all the other cases, the car unlocked after the previous one is better overall or has a max stat that is better than the previous.
However, all of the Interceptor's max stats are either equal or less than the Deliverator's. The Interceptor has 6, 4, 2 max stats in speed, handling and armor respectively, compared to the Deliverator's 6, 5, 4.
Disregarding the stats, does the Interceptor have another advantage over the Deliverator?
Whenever I tried to kill an boss, I usually took my Deliverator, it's deadly... But with Interceptor bosses it was just a bit harder to me as they escaped a little faster than the others, so I started using the Interceptor to unlock those achievements in Steam.
I didn't exactly know why, I just could get a clue from its description: it's made for breaking records; until I read some posts like these: IGN, GamingShogun. These posts are dated July 2012, when they released the iPhone update including the Interceptor car, Steam version included it from the beginning.
The Interceptor can reach higher speeds due to its extremely light build.
And this is also the feeling of some people like the one in this post, TimoVihola:
The cars have more stats than what is shown. For example the Interceptor has a very low mass (which makes it that much better).
Or one suggesting in the Steam Forum to use the Interceptor to kill The Adversary:
interceptor is the way to go, can keep up with him most of the time
So the answers to your question can be: Yes, it has an speed advantage due to it's 'lightweight design'.
The conclusion is that Death Rally gave to the cars more stats than the basic three ones (Armor, Speed, Handling) shown in the game.
