Question: In which city is the headquarters of the manufacturer of the engine used in the 1997 Rinspeed Mono Ego?
Sentence (from "HG-3 (rocket engine)"): Developed from Rocketdyne's J-2 engine used on the S-II and S-IVB stages, the engine was intended to replace the J-2 on the upgraded S-II-2 and S-IVB-2 stages intended for use on the Saturn MLV, Saturn IB-B and Saturn V/4-260 rockets, with a sea-level optimised version, the HG-3-SL, intended for use on the Saturn INT-17.
Relevant evidence: No