First dealer experience and I was sold a toyota tacoma that was certified with no proof and a fake car fax report when the vehicle had clearly been in some kind of front end damage. Also it had a broken driver window switch that was supposed to be replaced as GUARANTEED and stool this day hasn't been repaired.
They think you have a week to leave a car there for repair when you just bought it "certified" lol. What a joke!
Damn check engine light came on after two years causing me smog headaches. Point, I doubt they do anything at all to do much other that put this certified sticker on your car to charge you more money like car max.