I purchased a 4WD Limited Double Cab with the TRD Package in February of 2004. Thus far I have driven it in the snow, 3000-mile trip to Mexico, two trips to Las Vegas and a drive up the coast to San Francisco. It has driven superbly. I purchased the truck to be used as the family vehicle. I have read a few other reviews and can address the gas cap problem. Due to my trip to Mexico I purchased a locking cap (same as the 2003). In replacing the stock cap I read the owner's manual and noticed that even though it goes in one way, not a screw type, it does click more than once. Toyota recommends you turn the cap so that it clicks a few times. Apparently this helps to tighten the cap down. I had the "check engine light come on once, and quickly solved the problem by ensuring I click the cap a few times after I refuel. The light turned off on its own.
I had the truck loaded down, at least 1200 lbs., during most of my road trip into Mexico. I was surprised at how well it handled for being loaded down. The torquey engine helped when going uphill, but I did wish the engine had a little more power. The BF Goodrich tires that come on the TRD package are considered snow tires and as such handle well in the snow. I did not slide once during a trip to the local mountains. Aside from the lack of more HP/Torque the only other problem I have had is a squeak that comes from the bed whenever I hit an uneven road/surface. I have yet to take it in. Other than that the truck if fun to drive and safe for my family. The 15-mpg mileage is the trade off for having my family safe during our road trips. It is now July and I have put over 10,000 miles on the truck.