the S is for Sport. It goes into S4, this means it will use gears 1-4 If you push lever in S mode forward, you will See S5, this means it will use all 5 gears. If you pull, it goes to S4, S3, S2. This means the same, but wont go above the number chosen in the gear. Good for caravanning if you don't want it to constantly changing from 5th to 4th to 5th with slight throttle. S mode should give you longer revs in gear.....maybe...hard to test really as depends how hard you push your right foot.