A typical "low mileage" dance is completely hands-off. (i.e. no touching.)
A dance with fair mileage may include groping of the dancer's ass and breasts.
A dance where you're getting great mileage will include titty sucking, kissing, petting and digital vaginal penetration.
In some very rare cases, a dance including a hand-job, fellatio or full-on sex would be considered exceptional mileage. This, of course, could also be considered prostitution.
Dick: Who, Mercedez? She'll let you finger her.