At around 75-80 on open road, my 02 X type 2.5 manual trans has a slightly variable feel when I engage speed control. I can't see it on tach or speedo but it feels like I am in the air wash of a truck. Only there is no truck. Has anyone else noticed this? If I turn off the cruise and just keep my foot on the pedal steadily (this is flat open str8 highway), there is no such weird sensation. Thank you. --Tom

 

I had that feeling on a car I used to have, it was caused by a vacuum leak. I found it by accident on one of the lines going into the cruise control, it was like a pin ***** size hole.

 

Vacuum leak or it's right on an RPM/shift point. My auto does it, just so you slightly notice it, if I set it right on 120 kph. Not at 118 and not on 122. So, i don't set it on 120. Is yours at all different speed settings?

 

My car is a manual so the shift point is up to me! And this is not at 120 km/h but actually faster than that. I never use the cruise unless I am going at about that speed so I will have to try further experimentation. Thank you.

 

the faster you go the more vacuum is created....a pin ***** will loose more vacuum at speed.