I assume that you might get an increase if you take the outermost path on the exits ramps. This is only if you're coasting though. if you're on the throttle, then the inner most path would be better. Keep it safe though. Staying an extra foot inside the white lines might cost you .001 mpg, but the safety factor is definitely worth it.
Think of it as drifting without the drift part. You're simply changing the direction of your momentum. You're not creating or destroying energy, but simply changing the direction. If you change direction too fast, you'll lose energy to friction while if you change direction too slowly, you'll end up using more energy to go the extra distance.
I'm very interested to see some data about this so when you run some tests, post it on here so everyone knows.
Another thing is that all ramps are different, so this may change from ramp to ramp.
Who knew an exit ramp could be so complicated?
