We have a 1999 Legacy Outback in overall good working order (it has a rebuilt motor less than 3 years old which runs great).
When I depress the lever and engage the cruise control - the car goes into cruise control, but slows 4 to 6 miles per hour, depending on the overall speed. It will then hold that speed just fine. To cruise at 65 mph, I would have to engage it at 70 or 71 to allow for the slow down. It is bothersome to say the least.
Is this going to be a computer problem, electrical, or more mechanical - like a bad CC unit in the steering column ? Any other ideas would be great. Is this something a garage can electronically diagnose?