In 1996 Riley built an Indy Car for the newly formed IRL racing series. The Riley MK V debuted at the last race of the 1997 season in Las Vegas. The car was 4th quickest in practice until a crash in qualifying forced its retirement. The development of the MK V marked the return of Bob and Bill to the hallowed grounds of Indianapolis Motor Speedway.
A new car, the MKVIII, developed in conjunction with Reynard was introduced in 2002. The MK VIII nearly captured a win in its first event with Buddy Lazier and Eddie Cheever fighting for first place. The MK VIII won in the next round in Phoenix with Buddy Lazier going from "worst to first."