Futaba has just introduced this new HPS-CB701 servo which is intended for nitro buggy and car use.  The HPS servo series achieves amazing torque and low power consumption and is UR (Ultra Response) mode compatible.  Featuring a 3 piece all aluminium casing, it features metal 1-3 stage gear and a metal final stage gear. Source: Futaba [rc.futaba.co.jp]