Legal Question in Traffic Law in District of Columbia

Yes, sure sounds reasonable to me. (I would not, however, waste any of your time looking for a legal definition of what might constitute a so-called "compact car" in the District of Columbia. I'm reasonably confident that you won't find one.)

One might say in regard to this issue as one Justice of the U.S. Supreme Court is said to have opined on what might constitute actionable pornography in the Miller case back in the 1970's, i.e., "I know it when I see it" or something along those lines.

Same thing for a compact car (Wrangler Jeep)?

I agree. Be sure to request a hearing on the ticket. Then look up the definition of "compact" in Webster's. Bring the dictionary to Court and you are sure to win if you make a good argument.