2023 Chevy Suburban LS here (no fancy magnetic ride control or adaptive air ride suspension). I have almost the same symptoms as described by
@cmo12951. I will describe it as a vibration or mild to moderate shudder that occurs around 20 to 25 mph and again between about 45 and 55 mph. I can be on a glass smooth newly paved road and get it. It’s persistent as well—when driving st these speeds it’s constant. It’s noticeable enough that if I have a bag in the passenger seat, I can see it shaking back-and-forth and I can feel it up my back through the seat like the seat is vibrating forward and back.
It’s strongest when I gently touch the throttle to accelerate or let off the throttle. When decelerating from a higher speed to zero say for a stoplight or stop sign, as the vehicle downshifts around 25 mph. I get a pretty good shudder out of it. 4000 miles right now, have had the car for two months, I have a service appointment on Monday for another issue and will bring this up. I have the same concern, though, that if I don’t have a check engine light or a darned engine fire, the technician is just gonna tell me it’s road bumps. I know the difference; I had an 09 suburban and sold it at almost 300,000 miles.
