Cars are never a good investment from a financal standpoint ever, having said that you need time to yourself away from the kids and the woman Your car is you not the both of you. If you spend enough time with your g/f then she should have no problems with the fact that you have a hobby, that being said it should never go past hobby status, bills and food and stuff of that nature always come first no matter what ( sometimes that part sucks the most ) if you have some left over then enjoy the fruits of your labor. I do not spend my money wisely all the time and I have come to be ok with that, you should to. She probably talks about the clothes she bought from the mall all the time to and you put up with that, she should understand car parts are our clothes and we are as proud of them as she is her wardrobe. There is a middle ground where "we can all get along"
car people and non car people just have learn the barriers and stay within them.
I friggan sound like Dear Abby
