In a bowl, combine Sauvignon Blanc, mustard, olive oil, dill, garlic, sugar, and salt. Add pork tenderloins to marinade and chill at least 3 hours and up to 1 day.
Set up a grill with zones for both indirect and direct medium heat. Grill pork over direct heat until browned on all sides, turning as needed, about 10 minutes total. Move tenderloins to indirect heat area, cover grill, and cook until meat is done the way you like it, 10 to 15 minutes for medium-rare (145°; cut to test). Remove from grill, tent with foil, and let pork rest 5 to 10 minutes.