User blog comment:Legionwrex/How did Saren reach the Citadel?/@comment-1440333-20130507094740/@comment-2250460-20130507190648

I'm not assuming they used vehicles, I'm assuming the opposite. There is no evidence of a vehicle of any kind. Not when we saw Saren or when we were on the Citadel.

Saren should not have been able to Survive passing through the galaxy with no air and then come crashing out the other side into a wall. So I'm thinking this was just an oversight on the writers part.