 Since there are not a lot of cmax energi vehicles on the road compared to other models I feel this review will inform a lot of used and possibly new car buyers of potential costly problems with the cmax energi. I need a $1700 rear main seal replaced to stop an oil leak and $100 software update to stop the car engine turning on when the battery is full in L gear. Also I recently spent $500 on tires and alignment because we had really bad wear.GET THE CAR INSPECTED before you buy used. Have a mechanic pull back the plastic cover under the engine and inspect for leaks. Also test the car in Low gear immediately after recharging the EV battery to full and let it regen going down hill (more on that below). Check the wear on the tires! POSITIVE NOTE: I will say that outside of these issues, I do like the car. My wife likes it a lot too. Lots of upgrades and features in the car.I bought my 2013 cmax energi used with 98kmiles in 2015 for ~$11k. I have had electric, plug in hybrid and gas. The benefits of an electrified powertrain is lower maintenance costs and longer lasting. I figured this plug in should last longer than a conventional hybrid (like a prius taxi) with less major repairs if any at all. To my future self: don’t buy first year a car model is made. I get the feeling Ford slapped this together without a lot of testing or R&D. My Cmax odometer says 116k miles but the car display says 82k gas engine and 34k miles electric. I guess the rear main seal started leaking a lot earlier. This to me is a design flaw. Google cmax rear main seal leak and find the cmax forums and you will see many posts with rear main seal leaks at 28k, 48k miles, and even after repair leaking again 5k miles later! Thank you reviewer who posted at 160k miles his transmission went out and repair cost $7000! I realized that my leak could become a major problem if not fixed! But since I am out of warranty if I pay $1700 and it leaks again after 2 years, unlimited mile repair warranty I have to pay $1700 again. Also what if the reason that reviewers trans went out was not the seal!? It probably was though, oil leaks out, transmission breaks. FYI My car is only worth about $8000 on kbb.com with 116,000 miles.Ford did offer me a $300 discount on the repair after calling them many times and reminding them of all the Ford’s I have owned (4) in my lifetime. I also mentioned this would be the last Ford I buy if they can’t recognize this as a design flaw or help me with the cost of repair. $1400 is still a lot of money. Ford HQ made me take my vehicle back for an inspection before even trying to work out a discount (inspection was free with $30 oil change at a Ford dealer). I can’t afford the $1400 but will consider doing it soon. They only gave me 30 days to take their discounted offer.On to the tires briefly…Get an alignment! And rotate your tires. I’ve seen uneven wear in two of these cmax so I think its something you should pay attention to in order to avoid buying new tires before you need to. Not a biggie but something to pay attention to. We had tow in and tow out on our wheels and the tires were bumpy. Could have been the last owner not paying attention. Rides much better now.The engine turning on when the battery has been fully charged only happens in Low gear when I pull out of the garage and coast immediately down a slight hill incline the engine kicks on and revs pretty loud. I now never put the car in Low gear until the battery has depleted a little. When it’s fully charged I leave it in Drive not Low. A dealer told me it’s ~$100 to fix apparently it’s a software issue. Ford has no recall on this that fixes it. I have experienced this in another cmax energy as well as mine recently. If you pull over turn car off then on again the engine won’t go back on and it will run on Electric as designed. I hope this has helped. I hope Ford stands behind their products and stop just sending me to the dealer to pad their pockets when this is not a common issue in any other hybrid that I know of. I also hope that this car can get permanently fixed and I can drive it with no other issues for years until I purchase my next car. And to Ford’s credit I do respect they never took a bail out in 2008 but if the car buying public keeps getting penalized for their poor designs with expensive repairs I will not buy a Ford product again. I cannot understand why a 100+ year old company that has engineered and built 400 million cars cannot design a car that has a better crucial seal!