The Wankel engine has problems in fuel efficiency and emissions when burning gasoline. Gasoline mixtures are slow to ignite, have a slow flame propagation speed and a higher quenching distance on the compression cycle of 2mm compared to hydrogen's 0.6mm. Combined, these factors waste fuel that would have created power, reducing efficiency. The gap between the rotor and the engine housing is too narrow for gasoline on the compression cycle, but sufficiently wide for hydrogen. The narrow gap is needed to create compression. When the engine uses gasoline, leftover gasoline is ejected into the atmosphere through the exhaust. This is not a problem when using hydrogen fuel, as all the fuel mixture in the combustion chamber is burnt which gives nearly no emissions and raises fuel efficiency by 23%.