You either have to buy another vehicle or live with it. I have the same problem with the house. When both my roommate and I are at home to we'll use 3 or 4kwh of electricity per day total. When I'm gone for a couple days the rate increases to 8 to 10 kwh per day. I've dealt with it for years. It's too trivial to let it bother you.
Of course you can always buy a second vehicle just for hypermiling.
JJ