Assertion: automaker's car | /r/CapableOf | employ jet or rocket engines
Facets:
value: sometimes
type: TEMPORAL
Source sentences:
text: Vehicles using alternative fuels such as ethanol flexible-fuel vehicles and natural gas vehicles[clarification needed] are also gaining popularity in some countries.[citation needed] Cars for racing or speed records have sometimes employed jet or rocket engines, but these are impractical for common use.