Bought my pre-owned '06 M35x last Spring ('11) with roughly 60K miles - Had done a lot of research and had owned an older I-30 with 275K miles (replaced tranny @ 230K miles) - Had great luck, wanted to keep the brand.
During my research, I kept hearing others mentioning the Infiniti Elite Extended Warranty - I had heard about a dealer in Arizona (Scottsdale I believe) that had the best prices - I dealt with a lady named Courtney (Finance Mgr.).
I didn't/don't have a ton of discretionary $ - So the $1600-$1700 for the extended warranty was a hard pill to swallow - Especially for my wife - But we "found" the $.
Have MORE than recouped the $ invested (both frt. wheel bearings, CD plyr)
Overall I am very satisfied with my 2006 Infiniti M35x I brought it recently in August 2011 with 86,000 Miles on it and I currently have 98,000 Miles (Highway Miles) So far only had Minor issues. The first problem I had was the drivers side wheel bearing went bad $400.00. I had a very small oil leak but it was from Jiffy Lube forgetting to put back on the gasket for the drain plug. And my driver seat is broke but operational to drive the car safely needs a seat bracket and a new motor $1100. As far as the power train very nice acceleration but not as strong as the M45. Engine is loud but I like the way it sounds like a muscle car. Smooth ride overall very reliable on long road trips.
I have an 06 M35 Sport and love it. It handles like a true sports car. At 100+ mph it feel like it is on rails. The ride is a little stiffer of course but that is what the Sport edition is for. Fuel economy average is around 21 which is fine for this car. Seating is comfortable and roomy. It has 120K miles and still drives like it has 10K. If you are looking for a 4 door sedan that drives and handles like a sports car not sure you could go wrong with any of the Infiniti line up.
I have had my car for over a year now and the first year was great but now I am experience some quality problems. The rear brakes needed to be totally replaced with only 20,000 miles. Having some electrical problems as well. Passenger side power mirror not working, one power window not working and some of the dashboard lights intermittently come off and on.
Beautiful design. Ride and handling couldn't be any better. Car rides and handles like a little limousine. The features are bountiful and useful if only they worked. The nicest feature, the blue tooth phone went from virtually unusable due to an echo to not working at all. Had massive fight with dealer service who says it is supposed to be this way. No sense in having it if it does not work. Loaner car was filthy and our car returned unfixed with grease stains on driver's seat and center console.