Those half-length school busses that bring "slow" kids to special-ed school, or summer school.
"There were so few kids going on the field trip, they sent us on a tart cart, and the whole trip, people in cars were pulling up next to us and laughing because they thought we were retards."
bus used to bring mentally challenged kids to school
"Birdman rides the tart cart to school"
a limo, normally white and outside a night club
. so called because it is used to 'cart' a loads of 'tart
'look at all them sluts in their tart cart'
A very feminine vehicle (e.g. VW Cabriolet)
Trixie's sugar daddy just got her a new tart cart.