What gets better gas mileage a 750 cruiser or 600 sport bike?

The cruiser does, the sport bike is not made with gas mileage in mind.

the newer Honda shadows tend to get 45+ to lower 50 mpg as the cbr's tend to get 25 to 33 ish it might say better than that but who really drives like that if you want power Honda cbr 1000 is the right bike and that's about the millage you will get because that's what i was getting on my cousins and for the shadow my neighbor has the 2012 phantom and that's what gets for the most part

Look at the mileage real people get in the real world -- http://www.fuelly.com/motorcycle/

http://www.fuelly.com/motorcycle/honda/vt750c%20shadow -- about 50 mpg
http://www.fuelly.com/motorcycle/honda/cbr%20600%20f4i -- about 40 mpg

cruiser gets better MPG.