When my truck is in cruise I can feel it change speeds. It is a very mild surging/coasting I can feel in the seat as I drive. I am wondering if this is a "diesel thing". I also wonder if there is a fuel benefit from using the cruise when I can hold a steadier speed by foot

 

Mine does that when going down a hill. I'm not sure how it all works but it's normal for the truck to adjust the throttle to maintain the same speed up and down hills..............

 

This modulation of the throttle I can understand. I am speaking of flat ground and I can reach down and feel-w-my hand the pedal moving up and down way more than required to maintian steady speed. I have a Phord PS that does not od this.
Just kind of curious because it does not make sense this would help mileage?

 

I have noticed the same thing, very mild, but I can feel it.