To address reefdog's issue from the original thread, we decided to go with a less complicated form for the mobile site. We removed the drop-down switching and replaced it with a screen where you choose which car you want to fuel-up.
It means one extra step if you have several cars, but it also means that you can bookmark individual fuel-up pages on your phone instead of switching cars with the menu.
And it should mean the mobile site works on a wider variety of mobile browsers. (Not counting the T-Mobile Edge proxy issue.)