I basically just want cold drinks in the car. I am sick of paing $3 for 600ml of coke when I can get 1000ml for $1 at the supermarket. I have senn lots of car fridges... how much will a 12v car fridge effect my car? or fuel usuage? and how about a transformer to convert to 240v so i can use a notbook computer and cell-phone charger etc... will that use much fuel?