better gas mileage?

[h2wish]

hey everyone, is there anyway to make the hummer (h2) get between 15 to 20 miles per gallon without doing the diesel conversion? my dad really wants to get one for me and him to share he just wishes it wouldnt get such bad gas mileage. please dont say " you dont buy a hummer for gas mileage..." i know that but i really want one but he wont get one unless it can get a little better gas mileage. so are theres any little tweaks or parts you can do or get. thanks guys