The Manual states “When driving at your desired speed, set the cruising speed by moving the gear level fully down once then releasing”. But I found that if I am below the speed limit, it usually (but not always) sets to the detected speed limit, not the current (and desired) speed. Once in a while, it does set to the current speed. My local Tesla service could not figure this out, and said they would inquire about it. They didn't have another Model 3 available to compare. What speed does your Model 3 set to if you turn on cruise control when going below the speed limit?