I believe we should tithe and that it is necessary. I disagree that you have to do 10% of your gross income. There are more ways to tithe than to give money. You can be his hands and feet. You can give your time and your labor.
It is problematic to me to hear people who are posting on a forum populated by folks who are involved in an expensive hobby say "I'm going to pay my rent first." Pay your rent first that's fine. Even spend a couple hundred a month on your hobby. God wants you to be happy, to follow your bliss.
But, what have you done this week for him? Go to the car show nine weeks out of ten but on that tenth weekend volunteer somewhere. Pick up a hammer and help habitat for humanity build a house. Cook a meal for a soup kitchen. Do something. That's tithing.