Plug-in hybrids are similar to the hybrid vehicles mentioned above in that they switch between using the diesel/petrol engine and electric motor to improve efficiency. The difference is, unlike regular hybrids, plug-ins come with a higher-capacity battery and can be plugged-in to drive short distances on all-electric power. So, if you regularly make short trips and very rarely go on long adventures, this is a great way to keep your on-road activity free from fuel consumption.
If you don’t want to plug-in the hybrid you don’t have to. It will simply function as a regular hybrid.