Should I ask my relative to help buy me a car?

I want a car, I'm 18 now and my parents don't exactly have the money too buy me a car. Fortunately I have a rich aunt and uncle, and they live quite wealthily with a Mercedes sl series r230, and new fords, Chevrolets, they've also owned Porsches, my uncle on top of that owns a 1966 stingray corvette. So would asking them for help with buying a car, with compensation of me making monthly payments back too them for the car be too much? I'm not too fond of asking for help, but I'm in a situation where I've got my back against the wall on this one, and I'd like some advice too see what might be a good idea?

In your opening sentence you state, "I want a car".
But in your closing statement you state, "I'm in a situation where I've got my back against the wall on this one".

I fail to see how wanting a car suddenly turns into a "must have" scenario. But, whatever you do, I strongly suggest you talk with your parents first about approaching other family members for a loan. Stuff like that can drive wedges between family members.

If you are responsible and stick to your word of paying for your car eventually, ask them for the loan. If you are in a position where you know you are not going to be able to pay them back, you need to make that clear. I obviously don't know you but I have a brother who has asked for things his entire life and he never pays anyone back. I on the other hand have never asked for anything because I'm responsible and if I can't afford something - I don't get it. Sometimes, depending on the situation, being in debt is worse than not having what you want and in most cases family will help you but if you truly have no way of paying them back or don't plan to, be honest because in the adult world when you get a loan, you pay it back and you appreciate the fact that they are helping you so don't take advantage of their generosity because family or not, they are not obligated and it is not their responsibility to help you. If they do it out of the goodness of their heart, return the favor by honoring your agreement of paying them back in full and as promptly as possible. You don't want to be my brother, to be known as a louse.

It doesn't sound like you have differentiated between a "want" and a "need". Wanting something is not uncommon. I think we all experience that. You make no mention of needing a car or why. Is public transportation available where you live? Is a car needed to get to a job? Can you get where you need to go on a bicycle? (most people can by the way)

Next, consider what you are asking for. Is it a contribution or a loan? If you are looking for a handout based on their financial situation, you might want to re-think this. They became wealthy most likely because of hard work, sacrifice, education, investment and risk taking. Unless you are also engaged in these activities, you are merely taking advantage. Do you have a solid reliable plan for repayment that guarantees you will NEVER miss a schedule payment? Why can't you go through a bank?

You should consider all these things before asking them.

I say no. I think you will feel better and more proud of it if you find a way to buy the car yourself. However, if you take out a loan make sure to steer clear of predatory practices like high interest rates and long term loans. Typically I think it's best to arrange financing with a bank or credit union before going car shopping (if you're not able to buy a car in full).

However, it sounds like either your aunt or uncle is an enthusiast. If you have a good relationship with them you may want to mention that you're looking for a car and ask if they have any suggestions given your budget. They may have advice, or some good leads or can recommend a trusted mechanic for a pre-purchase inspection. And think about it if you were in their position. Would you like to have a nephew talk to you and ask for advice about buying a car, particularly if you're an enthusiast? And how would you feel about relatives asking you for loans? (Also remember, not all people who live wealthy actually are, and many people with more modest lifestyles are actually loaded, so don't assume your aunt and uncle have a mountain of cash available).