I love my Tacoma, but even on a good day the 18mpg was a little painful on the wallet. Since I drive 50~60miles a day to work, and my girlfriend is about ~800 miles away round trip, so I figured an economic car would basically pay for itself with the fuel saved. Ended up searching Craigslist about 5 times a day, and was able to jump on a 1999.5 Jetta TDI:
It had small problems with it (light bulb holder shorted, and oil pan drain plug was stripped) and the owner didn't know what was wrong with it, so I got it way under what the car should have be sold for around here. Best part: 3 fill-ups so far, averaging 45 MPG each time!! Never mind the amazing sound of the diesel engine
So the plan as of right now is to keep it stock as long as possible, although a straight pipe is very tempting! Over the winter, I may try to put some skid plates underneath with sheet metal just to cut down on some wind resistance, with the goal of reaching/surpassing 55MPG!