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