1987 RUF CTR Yellowbird Dubbed the “Yellowbird” by a group of journalists during a two-day test drive event, the 1987 RUF CTR Yellowbird also earns its name thanks to the canary-like chirping of this twin-turbo’s blow off valve. Just 29 of these cherished classics were built – but you’ll be able to take it out any time in Forza Horizon.