A 2025 Pebble Beach Concours d’Elegance winner, the Hispano-Suiza H6C Nieuport-Astra Torpedo’s unusual exhaust has been revealed. Commissioned by aviator André Dubonnet, this car features an early vacuum muffler designed by Steigboy Apparatebau. This unique exhaust system was used on motorcycles and some aircraft but also applied to cars, matching the era of a gentleman aviator’s racing car.
Source: https://www.thedrive.com/news/whats-up-with-the-weird-exhaust-on-pebble-beachs-best-of-show-car