First off, I have to save money to spend on gas to go on this trip. I don't have a surplus of cash, so if I go on this I probably won't have any cash leftover to spend on gas to go to the meeting. It doesn't matter if I still have gas left in my tank, I'll probably need that next week to go buy food and other things.
Its much more important to me to go on this run than to attend the meeting anyways. The meetings happen every month, I've never even heard of a MR2 mountain run.