Absolutely nothing. Bought it from a small dealership, and have had a blast with this vehicle.
A funny story here; when I first got the vehicle, I was apprehensive of Hyundai's reliability - mainly because there's so many Hyundai haters out there (all Toyota and Honda fan-boys will be quick to tell you), but I had nothing that could prove those claims true, in fact I had no idea what I was even looking for to go wrong.
One day to my disbelief, while driving around, I smelled something burning in the cabin of my vehicle. I stopped to examine, and I found nothing under the hood. I drove around a bit more and the smell got stronger, like a pungent electronic burning. I pulled over, and this time smoke was rolling out of the front of the car. I discovered a small fire at the bottom of the engine cavity, and after a moment of dead panic, I found the nearest fire extinguisher and blew the flame out.
I was shaking and so angry that I called the dealership the next day (after towing the vehicle to a nearby parking lot) and demanded that they do something about this problem. They were dumbfounded as the vehicle had a pretty decent history (only a couple of small collisions) and was well taken care of. Nonetheless, out of curiosity and obligation they called a mechanic over to look at the vehicle. He towed it to his shop and inspected the vehicle to find - wait for it - an oil shop rag stuck in the underside of the engine cavity. When he called, he said it was only a matter of time before it got hot enough to erupt into flames, but it was good that it did while I was near a fire extinguisher, because I had extinguished the flames before they had a chance to burn anything up. Not a single wire was singed. Thank God!
He looked everything else over and said it was a "very good vehicle" and gave it the thumbs up. He test drove it for an hour or so around town, to make sure nothing else was causing problems, and found no problems.
After a long moment of relief, and thanking God, I laughed to myself at the utter stupidity of an old shop rag catching fire in my vehicle.
I had the vehicle looked over and inspected a few more times by other shops in the area, and they all said everything looked fine.
My Hyundai Santa Fe has been a great little vehicle so far. I get 14 mpg in town and between 24 and 28 highway (depending on number and weight of passengers). I felt that I should comment on the vehicle early on, because I want people to be relieved that buying a Hyundai is a smart move.
Complaints I have :
1) Acceleration is vividly quick.
One tap of the pedal and you're surging forward to new horizons. Be careful to ease onto the pedal. Small, sudden taps will punch the vehicle forward - VRROOOM. The plus side of this is, the feeling you get when you accelerate is empowering. This allows you to pass quickly and effortlessly, while feeling like a he-man (or a powerful soccer mom diva).
2) In conjunction, the braking is sluggish.
I figured perhaps there's a bubble in the line, but after feeling it out more, I think it's just the how the brake system is designed. When coming to a stop, it's a good idea to plan one or two blocks ahead to let off the gas and glide, pumping the brake lightly and then generously as you approach the stop from a half block away. This will prevent unwanted wear on your brakes. I would definitely encourage a tighter brake response in this vehicle, it is probably my biggest gripe thus far.
3) The rear hatch sometimes gets caught.
Once in a while the latch hook will get stuck on the rear door (much like popping your hood but being unable to release it), and I'll have to keep pressing and pushing in, and then grabbing out to release it. A minor annoyance.
Everything else has been peaches from my perspective.
I'd also like to add that what I've discovered about the vehicle market and the Kelley Blue Book values, is that they are highly swayed by popular opinion. Honda and Toyota both have high marks and high resale values because there are devoted fans that have had older (the best) Toyotas and Hondas that have lasted forever.
However - just because the Toys and Hons of old lore have been great cars, that DOES NOT mean that the new ones are built the same way today. In fact, I feel SAFER buying a vehicle from a company that is constantly making strides to improve their build quality and construction, versus a company that settles on their old reputation. Creativity and workmanship tend to get stale after you've been on top for so long, unless you have a fighting dog-eat-dog spirit to keep it that way. It's obvious that many manufacturers don't have that any more, because of quality control issues now appearing in late model vehicles.
Toyota is not even a Japanese car anymore, and Honda has done nothing revolutionary in the past couple years. And since Hyundai is unfairly criticized and "stacked up" against these two manufacturers, I wanted to make this glaring contrast.
Hyundai IS a great vehicle. And they are a great value.
My '03 Pontiac Grand Am GT (see my review) was an extremely reliable vehicle, and I was sad to give it up, but I had to because of our South Dakota winters. In hindsight, with this AWD system I think that it will be a worthy contender this upcoming winter (and the heated seats will keep my bum happy).
If there are any updates to this vehicle (whether positive, negative, or neutral) I will be sure to post again after another 10,000 miles.
P.S., one last comment - after reading through the manual, I have learned A TON about my vehicle. Most questions you will have are in the manual. Take an afternoon or a lunch break to read through your Hyundai manual. You'll learn a lot about the vehicle that you never knew, and in fact it may save your life someday if you ever do break down (there are strict instructions for towing a 4WD Santa Fe to avoid ruining the trans-axle... this is a required read).