I understand where you are coming from. I have a 98 Cavalier that we are replacing with the TCH. The Cav has just over 50,000 mi and runs great. It's worth peanuts to sell. Buying a new car is probably one of the most idiotic financial choices you can make. I was going back and forth in my head too. For me, what brought me peace of mind:
1) I had a good honest look at the Cav and realized that while it's good shape right now, pretty soon it's going to start falling apart, rust just starting to come thru, etc. (Decide for yourself what you can expect from your truck in the next year or two)
2) For us, buying this car is not a terribly risky financial choice. I'm just an ordinary working guy, but I have enough "reserve" to see me thru if something unexpected happens (you might consider some "what if" scenarios if you buy the car to determine a way out, maybe lease instead of buy, figure out that if things go bad are you screwed or simply have to make adjustments to compensate).
3) Finally, and most importantly for me, this was never about simple transportation or smart money choices. It's about taking advantage of an opportunity to feel good in this short life. Feel good about having a nice new car. Feel good about something that's quite a bit different than anything I've had before. Feel good about a technically cool toy to play with. Feel good about something that will be safer to drive. Feel good about something that should reduce some pollution (what is this worth to you in your life?).