Nice set of guidelines for user experience design of mobile forms, including the one below.
“Europcar has a rather long list of pick up countries (139 in total) on their car rental form. Knowing that such a long drop down menu would not work well for mobile devices, they striped down the country list into 40 primary or most popular countries to make the selection easier and quicker. They didn’t just stop there. They took advantage of mobile devices’ built in location based feature to give users an option to allow the device to locate their current location and to find the nearest pick up station. It not only simplifies the form input, but also matches mobile users’ need in terms of how and when they would use the booking form (find the closest station and make a booking there and then).”
Link: Mobile Form Design Strategies (uxbooth.com)