There are three traits that are most important in a surveillance vehicle.
A interesting vehicle is a noticed vehicle.
I have heard of investigators not showing up to the surveillance and using the excuse that their vehicle broke down, or wouldn't start.
Must be able to fit in, in any neighborhood. Rich, poor, middle class, city or country.
There is are several vehicles that fits the above description to the t.
Bet you thought I was going to tell you what we use ;)