Good point - iirc charging efficiency is around 85-95% depending on the car/charger and charging speed?
Yeah, definitely, it's a bit **** how you can have a nice "weekend car" which does less than 1k miles/year, but pay more in VED than your repmobile doing 30k up and down the motorway every day.
The Govt does intend at some point to go over to a charge per mile system. They have even done papers and trials on it. Its the future and its coming with all these cars connected to the internet at all times. I can see exactly how many miles, when and on what roads I have driven my BMW on. Easier enough to come up with a charging system where you might get charged £1.50 per mile for being on the M25 at rush hour but on a rural country lane at 11am you may only get charged 20p per mile.