I live close to Palm Springs California. About 115 miles east from Los Angeles. I needed a car as it goes up to 100 degrees starting in the end of March out here, and my old car needed A/C which I was not willing to invest in. I WAS willing to order a car from Ford and pay cash for it up front, before delivery, to get just what I wanted, which was a 2017 (at that point) Triple Yellow, hard top, mustang 2.3L Turbo Ecoboost, automatic transmission. Every dealer tried to get me to buy a car off the lot, most in a different color. So I started looking for my car used. I found about 4 with the options I wanted, in a 350 mile radius, which pretty much covers all of southern California. EVERY ONE was a prior rental car being sold by a dealership. What I settled on was a premium package, leather interior, 9 speaker audio, automatic, in Triple Yellow. It had pretty cool machined face two color rims, 18". Heated and cooled seats. I can't remember how many powered directions my seats move in, passenger and driver seat are both like six way. LED lights, Pony Projector Package, dual climate control, and I chose the 2016 because it has the bigger touch screen in the middle of the dash vs. the 2015,( which I could have picked up for an asking price of $19,500. ) The model I chose has side impact air bags, toggle switches between drive modes, paddle shifters, automatic louvres in the front to act as an air damn when turbo cooling is not essential, my ECU tells me about boost, driver instrument cluster, multiple temperature readings from air inlet temps to transmission, boost, and TPMS etc, on the steering wheel I've got multiple functions for phone, radio, cruise control. I have power side view mirrors with turn signals, etc. It had 26,500 miles on a car that originally sold for $34,000. They wanted almost 27K. I knocked them down to 25.5K including tax title and tag, and gave them my 1998 Mercury Mystique with 58,000 miles on it, which was kept outside in downtown Philadelphia, and suffered through many rains, snows, freezes and thaws on heavily salted roads. What else they gave me, and the moral of the story is that since it was a ONE owner car, they gave me a 100,000 mile Ford CPO (Certified Pre Owned) warranty on the power train. Originally the warranty was something like 35,000 miles. That gives me about 4 years of driving under warranty. It has been stellar. The only things I've noticed is that the windshield is pitted. Out here in the desert you get a lot of blowing sand. So after about 6 months the dings in the front paint started showing from where the dealer touched it up. It still looks great, and someday I was going to have to paint it anyway. The windshield I will correct after I move out of the dessert. Other then that, my prior rental car has been flawless. If you can get a CPO car, I would say you have little worries.
Of course an extended test drive is in order, take it up to 80 mph to make sure there are no vibration problems. Ultimately, since Ford put much needed improvements in the 2018, more horsepower, they worked on the rear end hop which caused me to put in the street handling package from Ford Performance, (really helped) and I went with a CAI to try to help the lousy low end performance to no real avail. (Ford Performance to preserve warranty) I would wait to buy a used 2018. Unless you are going for a GT, which has all the power you will need on public roadways. By all means buy used, but get CPO.