Im loosing between 1 and 1.5 mpg on sport mode over normal on my 2.0T after 100 miles. Its fun to drive on Sport though. But when trying to coast in hangs on to gears so it slows down fast which is probably were you loose most of the mpg as you need to accelerate more often. So for me sport...
24.2 on computer and 23.6 using 10 gln and milage calc with stock steelies. Havnt reached 1000 miles yet. In the next week or so ill be putting on my 255/65/17s and am sure will drop a couple mpg. Will have to adjust mpg for tire size