Both battery electric and plug-in hybrid electric vehicles are able to add range from an electric source and drive on electric only. The difference is that PHEVs have both a gasoline-powered engine and a battery powered motor, while BEVs lack the gasoline motor.
PHEVs appeal to the risk-averse idea of having a redundant powertrain. But there are several downsides:
- Maintenance of two powertrains (BEVs have almost no powertrain maintenance)
- Greater complexity – more things to go wrong
- Continued dependence on gasoline – we’ve passed peak gasoline and the supply chain will start contracting, meaning greater costs and eventually shortages and disruptions.
- Since the battery is much smaller in a PHEV, it undergoes more cycling (fully charged to low charge) and will therefore wear out sooner.
- Driving mostly on electric (the desired use to take advantage of the plug-in feature) means the gasoline engine is used much less often. This causes the engine to be used more frequently in cold-start, high power situations which are hardest on an engine.
- Driving mostly on gasoline confers no advantage over a hybrid vehicle and does not justify the added expense and complexity of the larger battery and charging hardware.