I got a 300 quid saxo when my commute increased, i ended up driving it all week... and well, when big mileage was to be done, it made sense to put it on that and not the zed. Also, bnq trips or, well anything where i'd be throwing stuff in were done in the saxo. Then, if I was going out that night and taking the car, it made sense to take the saxo so i didnt have to park the zed in town and get it scratched etc.
Before i knew it I spent zero time in the zed and it was a bigger waste of money sitting there losing value than if i'd just driven it.
sell it and buy a diesel or keep it and stomach the cost.