Rally cars have recognizable engine noises that are distinct from other types of racing vehicles. The sound of a rally car is largely due to the engine's turbocharger, which increases air flow and horsepower. The turbocharger is designed to reduce the amount of exhaust gases, producing a 'whistling' noise. Additionally, rally cars usually have small exhaust pipes, which also contribute to the engine sound. Lastly, many rally cars feature a 'blow off valve', which releases pressure and further contributes to the unique sound of a rally car.