--The only major thing that has gone wrong with the Malibu was how the brake rotors rusted over during tire service at 40,000mi and had to be replaced, along with new pads. This ran up to around 300-400 dollars in service fees. However, most American cars seem to have this problem with brakes (it happened to our '03 Ford Escape too.)
Some (very) Minor Things:
--The car on occasion will not turn over immediately when starting the car. No side effects have occurred though.
--Occasionally a seat warmer will turn on automatically. No Biggie, you can just switch it off.
--I'm a teenager driving an "old mans" car. I get insulted from time to time, but overall I'm attached to this car.
--The gas mileage on this car is outstanding. Highway: 26-29 MPG and 24-25 city. Extremely efficent for a mid-size sedan.
--Acceleration is great and RPM levels are low, making the engine perform well (2,225 RPM at 80 MPH!)
--The computer is extremely helpful and lets me know about gas mileage, oil level, trip mileage, and any hazards (gas caps, door ajar, etc.)
--Onstar is cool, but unnecessary. XM is nice.
--Heated Seats + remote Starter = Top Shelf.
--The leather seats have held up extremely well, and I keep the interior clean.
--Big Trunk
--Decent Sunroof
--Side Curtain Airbags are a great additive to safety.
Rotors rusted over? That is very odd, I've never heard of that happening.