Here is the full list of all 7 Omega Racers achievements.
Beat time 0'15,000 in Miami.
Beat time 0'24,299 in Orlando.
Beat time 0'28,400 in Ouray.
Beat time 0'25,000 in Marfa.
Complete challenge 3, your first obstacle challenge
Complete challenge 4, overcoming bronze time
Complete challenge 6, overcoming gold time