Car over time slowly started shifting really hard into drive like a jolt and occasionally shifting faster than needed. This happened for like 1 month until the car got stuck into first gear. It would immediately stall out in 2nd and slam on the brakes. I drove the car 5 mph with hazards in first gear to a Ford shop. Their transmission expert was out so it took 1 week before someone could look at it and another 1 before they could start it. Once the repair was done the car has been fine for the most part. It was covered under the powertrain warranty since it was under 60k miles. I got lucky

2018 Mustang 2.3L premium package w/ the 12" cluster. I am an old gear head and know when a transmission is having problems. Worked on cars and race cars for years when I was younger. I have the 10-Speed select transmission. What a piece of crap.

I've been a Ford man all my life. This may change me. Been back to the dealer 3 times with multiple phone calls with no resolution because Ford won't recognize there is a problem. So the dealer's hands are tied. The trans will make a clunking sound going into gear. Sometimes I'll go into D and the car will not move for say 4-5 seconds, then lunge forward hard. Also my gears will change 1-3-5 then 6 in order. Sometimes at slower pick up it may go into 4th. When it goes from 3-5 feels like it downshifts then goes into 6. I have no problems with the higher gears.

Sometimes when going mid speed, say 35-40, it will be in 7th or 8th gear. WHY? Then coming to a stop from 35-40 in 6th to 8th gear. Downshifts real hard and you can feel it in the pedal. WORST transmission I have had. This is my 5th Mustang and worst ever. Had a 2016 with 6 speed trans for 3 years. Did not take it back to the dealer - not once. Not for anything. If I knew the 10 speed was this bad, never would have bought the car. By the way, the F150's are having the same problem. There is a lawsuit in Illinois on the F150 for this issue.