I'm mad at my boss for making me drive to a different work site on my own time and gas.
Why does that make you so angry?
Because it's unfair that I have to spend my own money on this work related task.
I completely understand your frustration. Most companies will pay you if they require you to travel somewhere far away for a work assignment. Talk to them and see if there's a program like that.
Nah. I'm just gonna half-ass my work instead. That will show them.
I know that you're frustrated and angry at your boss for making you spend your own money. However, not taking your work seriously and doing a bad job on it will make you look bad and could even cause you to get fired. Do you want to lose your job?