I FIGURED IT OUT, WITH HELP: The Cruise Control with Adaptive Cruise Control (ACC)
off is screwy on the 2021 Mustang (and earlier models, for all I know). You MUST set the
new speed in one-click increments, that is, if you are doing 70mph and want to increase
speed to 75, you must click SET + five times. Holding down the SET + or SET - rocker
button will increase your speed in 5MPH increments, but hold it down too long and all of a
sudden you are increasing your speed from, say, 70 mph to 85 mph. The Key: you must
look at the little speedo icon on the speedometer portion of your instrument panel to watch
what your thumb has done to your mph. The Mustang Owner's Manual is totally silent on
these procedures, and WWW.HELP.FORD.COM tells you about the individual click method
to increase your speed but does not mention the 5MPH increment thing when you hold
down SET + or -. I'm fortunate to live about 14 miles from Ford World HQ, and a Ford
engineer friend of our son clued me in on how to use cruise control on my 2021 Mustang
10-speed automatic with the Adaptive Cruise Control turned off.
2 people found this helpful.
