Consider a wind turbine placed alongside a road in a location with no wind. If a vehicle drives past (without loss of generality, at a constant speed) the turbine will spin and electrical power can be produced. The power produced is obviously supplied by the vehicle. As compared to the case where these is no turbine, the vehicle will necessarily consume additional fuel to maintain constant speed as some of the vehicle's power is captured by the turbine. My question is this: What is the mechanism which causes the vehicle to consume more fuel?