He not only is not thinking about a future with someone else and/or a family in the future, but he's not being very realistic with the way the economy currently is. Most people are trying to eliminate their debt so that when things get even tighter--it's predicted that taxes are going to rise 52% to start paying for ObamaCare, and that's going to impact everybody--they don't lose everything. He needs to look at and start living within his means. Just because he likes the car does not mean he can afford OR that he needs it. There are wants, and then there are needs. The wants are usually what get people into trouble and into debt way over their heads.
Are you living together? Do you share the expenses? Or is he living with you and you're paying all the bills? If he does go ahead and buy the car (against your wishes), is he prepared to get a second or even a third job to help bring extra money into the household, since he's the one who's adamant that he needs this car? Or does he expect you the carry him and pay for everything?
Believe me, things are going to get a lot, lot worse before they get better. Those who are going to pull through these tough economic times are those people who can put the shiny toys on hold and learn to live within their means.
And as someone else mentioned, if you haven't sat down with him and talked frank talk about where your relationship is going, if there's a future with the two of you in it, and what your--and his--expectations are money-wise, then you're heading for lots of hurt down the road.
Trust me. I'm going on 13 years of marriage, and money issues is the one thing that is always, always there. We don't buy anything expensive but we're still barely left with any money--and that's after the bills are paid.
Buying something as expensive as a new car and then having no money/wiggle room left over after paying for it/the bills--he's letting that shiny new car cloud his judgment on what is the right thing to do. Is he going to go dumpster dumping for his food? Go to the Salvation Army for his clothes and other goods, because he can't afford anything once he pays his car bill (and let's NOT forget that his car insurance will probably go way, way up. Has he checked into how much auto insurance is going to cost him on that shiny new car? Has he looked into how much four new tires will cost for this new car? How much this particular car brand/model will cost him for various repairs? What is the gas mileage on it? Will he save gas money, or will he spend even more on gas to drive it?)?
It sounds like he needs to do a lot more homework before he brings that shiny new car home. And if he refuses to talk or listen to you when you point out the above facts, then I'd say it's time to move on. You don't need his poor money management to drag you down with him. Because once you're married, his debt is your debt. Better to learn now that he can't handle it.