Given current technology, what is the saturation level in the on-road vehicle market for PHEVs?
Although availability is currently the limiting factor, we will ignore it for now and assume many more cars will arrive soon. Considered only from a technology perspective, the saturation point for PHEVs could theoretically be 100% as PHEVs don't require any changes from the driver. Even plugging in, while the whole point of the vehicle, is not required. The most likely limiting factor is cost. The extra batteries (their price and weight) make a PHEV more expensive than a similar gas car. Similarly, the gas engine and all of its trappings make a PHEV generally more expensive than a BEV, although they are hard to compare directly because the ranges are not equivalent. At some point, the premium for a PHEV will be small enough that most people will be happy to pay it to avoid the anticipated fueling costs of a regular gas car, as well as the other disadvantages of burning petroleum. For some, that point is now. If gas prices rise 50% (or the premium is lowered by a similar amount), that point would probably be reached for a majority of buyers. If gas doubles, that theoretical limit of 100% may become a reality. PHEVs already have to worry about BEV competitors. If BEV refueling issues go away--whether through a network of fast chargers, or battery swapping, or new battery chemistries with great range--the simplicity of BEVs may win many converts from PHEVs.