A hybrid is the sensible answer, but you do have to factor in that you're carrying around two drive systems.
The wife's car is a full hybrid albeit not a plugin. The electric motor/battery is tiny so it only goes full electric mode in towns and other low load environments and then only for a few miles. It also has a horrible automatic gearbox, ok, all automatics are horrible but this one is particularly detestable.
Environmentally it's hard to justify as (for us) it rarely exceeds 56mpg, the regular petrol or mild hybrid version almost does that, but at least it's not spurting out too many noxious fumes in towns or stop-start traffic.
In retrospect a car with a bigger electric drive train would have been better, I quite liked the Dacia Duster full hybrid when I tried it.