The only thing that I am not sure about: WHO is that in the corner of cap 3?? Blue-y shirt and cap??
My best guess, based on sleuthing of promo videos of this episode, is....
Not - Dave (black t-shirt) & Rachel (blue tank & brown cap, also aqua shirt)
Not - Art (red t-shirt & red bandanna) & JJ (red t-shirt)
Not - Mark (white sleeveless shirt & black/yellow cap, also long-sleeve gray) & Bopper (white tank)
Not - Brendon & Rachel, both can be clearly seen (duh!... lol)
Not - Kerri (gray tank) & Stacy (gray tank)
Not - Nary (yellow shirt) & Jamie (not seen, but it looks to be a guy in that pic anyway)
Not - Ralph (gray w/black sleeve shirt & blue bandanna) & Vanessa (white/pink/aqua shirt)
Possibly - Joey & Danny (white tank and black tank... I can't tell them apart!)
Possibly - Elliot (blue t-shirt, no cap) & Andrew (black shirt)
IF, Elliot DOES have a cap, it COULD be him. However, we've had no evidence that either brother wears anything on their head during the race to date.
Or, it could be Danny (?... the lighter haired one) IF he wore a blue t-shirt over his tank and stripped it off before the street race. He was shown having a white front/black backed cap with a green bill at the start of the race JUST LIKE the one in that cap from promo2; however, I didn't see him wearing a blue t-shirt in any other video (including the full episodes).
Otherwise, the only other possiblity is the bystander that can be seen in this cap (same shirt but can't see clearly if he's wearing a cap):