My one-year wedding anniversary is less than one week away. Trust what everyone here is telling you, don't hide or sneak around about money or anything else. It's a great way to start to start a fight and ruin a relationship. Put yourself in her shoes. How do you think she would feel if a year or two from now she found out you were secreting away money to use on whatever. She would feel as though her trust was violated. Once you lose trust, you start to question everything your spouse is doing.
My (opps) our Z needed some major undercarriage work this summer. Keep in mind we were also house-shopping at the time. When I told my wife I needed her to help me drop the car off, a discussion ensued about what was wrong, what it needed, oh yeah, and what I thought it would costs. Given the figure I threw out, (At least $500 or $600 labor) she was taken back that I was informing her I was doing this without discussing it. Keep in mind; I am the cheapskate in our marriage. If the rolls were reversed, I would have been upset with her for not discussing it first. I admitted I was wrong, because I believed I was, we discussed it, it fit our budget because I had saved for it, we moved on.
In our marriage the biggest problem is communication. Don't get me wrong, our marriage is rock solid, we love each other very much and have a great relationship, but when we have disagreements, or fights, 95% of the time it's due to miscommunication. 1). If you really love her and love your hobby, you need to let her know that on both counts. 2) You also have to realize that you can no longer do whatever you want with money. Marriage means what's mine is hers and what hers is mine and as someone stated earlier relationships are about compromise.
As far as Z's go, my wife is not a big car person. She's not a guy . I try to involve her as much as I can and she has been a good sport about it. We have plans to eventually buy a Z or Datsun roadster for her. She'll drive it; I'll work on it. But once that happens it's not just spending on "my" (I keep telling her its ours) car; we are restoring/ modifying our cars. Big difference. We are both members of our Z club. Does she go to every meeting - not even close. She barely goes to any. But I tell her about them when I get home. Mention names, what's going on with people's families and cars. I try to get her involved in the club events and outings that other women go to. Part of what I think a club should do is sponsor family oriented stuff to involve spouses, kids, etc. She has come to shows and sat behind the car with a book. Guys talk to her more than me???? HEY!
I guess my morale is, unless you hit lotto, your "spending responsibility" will have to change. Let her know it's really important to you. Until she's out of school and making money, your project may have to slow down or take a back seat for a while. That doesn't mean you have to give it up, it just means that your marriage is more important than a car. Not always a bad thing.
A possible suggestion: a friend of mine told me this, before I got married. Once you're married and establish your budget - after everything (including savings) is accounted for, part of your weekly budget should be for lack of better terms, an allowance. Whether it's $10, or $1000 (dream), you each get the same amount and it's yours for whatever. So if I save it for a month and use it to buy car parts, that's my money to do with as I please. If she wants to buy Cosmo every week or save it for a month and go to the spa, that's hers and I have no right to tell her what to do with it.
This is simply my very humble and ignorant opinion. I'm not an expert by any means. Just remember, like an old Z, a marriage takes constant maintenance and care. If you put in the time and energy it will be a great car/relationship. If you do a half-ass job, you will have a half-ass marriage and a clunker. That means constant, constant open communication. You have to talk to her and you shouldn't hide stuff.
Health and happiness to you both.