There are a lot of cases of successful U-turns. In fact, Brook & Claire from TAR17 were the 1st ever team to survive a U-turn (but that's only because the W-turn was introduced right then and there). Bill & Cathi would've been the very 1st to survive a U-turn, although the subjective term of successful applies to Bill & Cathi, as Ernie & Cindy's reason of U-turning Bill & Cathi is for the latter not to beat the former in a race for 1st.