Put at least $90,000 into savings for college expenses.

Buy a car that needs some work, say 150k miles, broken shocks, leaky brakes, needs an oil change, bad interior, needs a head gasket change, etc. You should be able to buy that for $2,000-$3,000.

Spend around $1,000 to fix it up. YOURSELVES (of course, if it needs a new transmission, I wouldn't do that myself). It's pretty easy to buy a couple hundred dollars worth of tools, some parts, spend some time on youtube learning how to do the work, then do the work. This will teach you how to fix a car, in case it breaks down again, you'll have the necessary tools to do the work, and it's an excuse to spend time together.

What my parents did for me was first to buy a $700 1987 pickup, which we fixed and sold for $2,100. After that, we bought a 'nicer' 1998 Chevy K1500 pickup, which had very little brakes, leaked coolant, had no shocks, bald tires, needed a new windshield and wipers, etc. We removed and pressure washed the interior, scraped off the Jesus decals, replaced the shocks, head gasket, welded a new muffler, replaced brake lines, bled the brakes, replaced the headlights, wired a new stereo, gave it a nice cleaning, and with around $800 worth of parts and a ton of time spent with my Dad, the formerly $2,500 truck turned into a $5,500 one.

I highly suggest doing something like this, and if you don't live where it's snowy 6 months out of the year and you need 4WD, I encourage you to do this to a cool car, like maybe an older Camaro, Mustang, or even an import. You'll make a ton of good memories, learn skills, and save $90,000!

Guess what OP, I'm going to answer your question. Get him a Tesla Model S P85.

It's about $80k at the base level, so I took the liberty of adding a couple of extra's:

• All-Wheel Drive Dual Motor ($5k)
• Tech Package with Autopilot ($4,250)
• Premium Interior Package ($3,500)
• Ultra High Fidelity Sound ($2,500)

Total price: $99,320 ($91,820 if you live in a state that has a $7,500 tax credit)

If you want to fiddle with the options, you can do that in the Model S Design Studio .

Why a Tesla Model S P85?

I had the immense pleasure of testdriving the Model S P85 several weeks ago and here's what makes it awesome from a young person's perspective (I'm 23):

It's an absolute fucking beast. This car does 0-60mph in 5.2 secs, while not as fast as the new P85D it still accelerates faster than a M5 or a Porsche Panamera. Because there's no transmission box the acceleration is smooth. It's also instant. While true that you can't sustain sports car (Ferrari) level speeds in this thing, that might just be good given you're gonna give it to a kid who's probably going to wreck it.

It's the future. Just test drive it, OK? It's a fucking spaceship. It has a giant freaking touchscreen for controls. Your iPhone interacts with it, it has a shitton of next level features. It updates over-the-air, ffs it's awesome. Just...just read the Oatmeal about it:

Source: What it's like to own a Tesla Model S - A cartoonist's review of his magical space car - The Oatmeal

It has the perfect image. You want to buy your kid an S-class...what is he, fifty? No? Perhaps the wife of a Russian oligarch then? Again no? A Rover you said? That's for soccermoms. A BMW maybe? Well if he's a drug dealer I guess you could go for the black on black Beemer look. Tesla's aren't just cool, they're the "look at me, I have a great Sedan that can smoke your ass but is just as modest as an Audi...oh and it's all electric, but not in a Prius kind of way" car. The only people who shit on Tesla's are the "HURR DURR MY CAR NEEDS TO MAKE LOTS OF NOISE AND TIRESMOKE, HURR DURR MUSCLE CAR" people. Screw them, they are going the way of the dinosaurs.

Last but not least...

It's a safe car.

• http://www.teslamotors.com/blog/model-s-achieves-euro-ncap-5star-safety-rating
• http://usnews.rankingsandreviews.com/cars-trucks/Tesla_Model-S/Safety/

In conclusion...

This car has awesome specs, a sweet brand image of luxury and forward-looking design without the negative connotations of other luxury brands, and it's a safe car.

While Nick Malik's answer will probably be best for your son's future as a likeable and functioning member of society, I don't think the car will actually matter much when it comes to how he turns out. He's been formed already. Anecdotally I used to know a guy whose parents - supposedly - offered to buy him a Lambo as his first car. They didn't, he was still a douche most of the time. So fuck it, there's your car and there's your answer.

My first car was a 1965 Rambler American four-door. The year was 1978 and I bought it for $450.00 (That's USD). I saved my money from my job washing dishes to buy it. It was old, it had a slant-six engine, and I had a lot of fun with that car. I did have to have it worked on every so often.

I paid my own tuition and fees in college too, but at the time the cost was $240.40 a semester. Books were not included. Very cheap, but it was a good university.

The idea that you would spend $100K on a car, let alone for your kid, speaks volumes to me. You are not preparing you child for life. Let him or her save, plan, and maintain his or her own car; your advice and guidance will, of course, be invaluable. I guarantee that your child will be proud of that car, even years later. I have seen too many spoiled kids wrecking cars and treating them like disposable razors.

No situation is resolved by throwing money at it; in raising children it is positively harmful.

It Can I just say something? People - even rich people - who spend 100k, hell who even spend 20K for their teenager's car ought to be be in the old fashioned pillories, so folks can throw rotten fruit and old tomatoes at them.
You don't want to spend that much money on a teenager, because you are sending the wrong message. The message you should be sending is, if you want a nice car, you have to buy yourself one. You have to earn it.
But you want them to be safe.
Buy them a used Volvo.
Volvos are built like tanks. And they are pretty good cars. And they will usually go to 250K, no problem.
But, in my humble opinion only, even if you are rich enough to spend 100k -hell even 20k - for your teenager's car, YOU SHOULDN'T!
You are spoiling your kid.
This is where parents who do things like this belong:

Update: I see the question has been changed. Now the parent says the child is paying for the car, he just wants advice.
Oh really. And where did the "child" get this money from? Trust fund?
And whose money was that?
I stick by my original answer. Spending 100K for a car is asinine, and countenancing it is bullshit - in my opinion.

I love how people miss the question entirely and try to push their agenda.

I do love how @Jason Manson answered.

The question implies you have 100K and chances are that you aren't hurting for money. That's awesome and I'm not going to lecture you on what is the right thing to do, because only you know that as a parent and how the kid has been brought up.

Do I question the validity of giving anyone $100,000 vehicle? maybe, but that's discussion for another question.

I would actually get two cars for him. One worth around $20,000 and the other around $60,000 then let him have $20,000 to use in the vehicles. Take a trip, modify it, customize it, etc.

If you go with the one vehicle approach and if I were a teenager, a Tesla would be killer.

As a parent I would focus on safety and how the car will be used by the kid and perceived by others. If your kid is in the circles where the other kids drive similar cars then he'll fit right in. Otherwise it could make him feel awkward to drive a 100K tesla when his friends and peers are driving 8 year old Camrys, 15 year old civics or have no car at all.

At the end of the day, why don't you just ask him what he wants and see where that conversation leads. Go test drive the ones he wants and then make a decision together. You could save yourself some money if he just wants something for 1/2 the price. He'll be happier that he made the decision and you'll be able to put that money back into the machine that made it for you.

Note: Questioner originally made clear they (the parent) was paying all. Revision implies the parent conflates a child paying for something, with a child paying half of something. Still, I commend the parent for having the child pay half. I do wonder how a child comes up with $50k in actually-earned money.

My answer to the original question, for what it’s worth:

What do you ultimately want for your child? In 100 years, do you want people to be happy your child lived? Do you want people to mourn his death, after a long and productive life that left a vast, beautiful legacy?

Then buy 20 used Honda Civics, and make your quite frankly worthless kid find 19 needy families to give 19 of those cars to. Then make him earn the 20th car in some line of work that pays less than $20 an hour like a goddamned human being. If you do all that, your kid might overcome the handicap of being born to someone who's hell bent on spoiling him, and actually grow up to deserve his share of this planet's oxygen.

Note: I know your kid's not worthless. He's just worth about 100 times less than you're ascribing to him. That $100,000 could easily fill all your teen's needs, at $5,000, and leave you able to buy 19 cars for 19 other families with 4 people each. And those families include children just like your own. And a car would improve their happiness much more than your teen's. If you know which kind of family I'm talking about, they spend six hours a day commuting because they can't afford that car. They work hard. Their kids and they live very diminished lives because they're unfortunate, not lazy. They're certainly not any lazier than your teenager, and unlike your teen, they have innocent mouths to feed.

So that's 76 people you're shortchanging when you dump all that money, into one car, for your one kid. And they need cars more than your teen does, so, in a strictly ballpark sense, you're overvaluing your kid by at least a factor of 100. Stop doing that. If you don't, then your kid will be the hood ornament on some barbarian's dune buggy come the apocalypse. And I know at least 76 people who will see him crying and begging to be untied from the hood, given some shade and water and human consideration, who will just point and laugh, and laugh and laugh, and then drink another sweet sip of cool water from the bowl they made out of your skull.

Or, you know, Honda Civic now. They're good cars!

I wouldn’t recommend dropping $100k on a teen’s first car. Teenagers are still developing the decision-making skills necessary to drive without getting into a collision, and even an attentive teen still faces a learning curve when driving on their own for the first time. Add to that that teenage boys are much more likely to drive recklessly (hence the higher insurance costs for them) and you have a high possibility of him crashing the car, wasting that $100k and raising his insurance costs for the next several years (prices go down when you turn 25). $100k is a LOT to spend on a car, and at his point in life it could be saved for things like college or a house.

That's an easy one.
It's well known that the cost of building a care from individual parts is far higher than the cost of an assembled car.
Choose any car model where the total price of the parts bought individually (along with any necessary tools and test equipment) is about $100K. Buy the parts. And have your teen build their own car.
This will help develop serious life and technical skills, and they will have complete confidence in their ability to maintain and repair the car.
Plus, you can count on them being a very safe driver, so as not to risk damaging the car after working so hard to build it.

I hate giving advice to people on how to raise their children; there's no flawless technique and something that works for me may not work for you. That being said:
I don't think you should stick to the price tag when buying a car for your teen. You should try to meet his/her transportation needs in a form-factor affordable to him/her.
What do you want your child to be? An independent person, able to live by his/her own means or someone that will live through your money as long as you live?
I tell you, I'll only attain a feeling of accomplishment with my daughter on the day she will leave my house and tell me she doesn't need me anymore. I want to be always there to listen to her problems and reassure her, not to provide for her eternally.
Does your teen has an allowance or a job? If so, buy him/her a car he/she will be able to keep with his/her earnings.
Teach your teen the real value of money. Teach that he/she must work to get his/her money, even if he/she is a heir.
If your teen fail to understand these values he/she will end up in poverty, even if you leave him/her a vast sum of money.
Sorry if this seems a little too harsh.

Tell him you'll match the dollars he earns for his own car up to $5,000.

Use another couple thousand to send him on a trip to Tijuana, where he can see teens who literally live on a massive trash dump and have to get by on what they scrounge. Or to the Dominican Republic, where teens live in little tin shacks in the middle of a field of sugar cane, and they're thrilled to be there because life is so much better than in Haiti, where they came from.

Keep the remaining $93,000, or use it to start a program that sends entitled kids with no clue about the world to places where people with nothing still live joyful lives.

That's a bit much for a first automobile for a teenager, but if you have that sort of money to spend, I would suggest 2014 Tesla Model S.

Your teenaged son wants to buy his first car and wants to know what you would buy for yourself within his set budget? Wow. That's something you don't hear that too often.

If your son really wants to buy a car that you would buy for yourself, then it could be an opportunity to positively influence his choice.

With regard to the car that you would get personally, do you really have no idea as to a car that you would buy for yourself? So much so that you have to ask here for suggestions? The mind boggles.

I could only suggest that as a mature parent, you might not select a vehicle that's the stereotypical black or red, with the biggest, shiniest wheels, the biggest and noisiest engine, the biggest and loudest bass-loaded sound system, and the fastest speed capability that you can get for your buck, full stop. I would like to think that you would be selecting cars for yourself based on safety, reliability, performance, and comfort.

I would keep in mind though that with regards to the performance of a vehicle, a young teenager, no matter how smart or conscientious, simply does not have the experience, wit or wisdom of a veteran driver.

Everyone thinks I'm being snarky when I say this, but I think one of the best cars for teens is the Smart Car. It's safe (essentially a crash cage with an engine made by Mercedes-Benz), fuel efficient, it can only carry your teen and one other (packs of teens in a car is asking for trouble), and it can't go very fast at the top end (teens don't handle powerful cars well).

Considering that one of the leading causes of death for teens is auto accidents, I'm inclined to get something that can't get itself into a ton of trouble. Because if there are two truths in this world, it's that teens can get themselves into a lot of trouble, but they are terrible at getting out of it.

Please, please, please tell me this question is a joke.

Even my wealthiest friends wouldn't spend that amount of money on themselves for a diminishing asset. Much less for someone who has yet to understand the value of the work involved in generating $100,000 for the vast majority of Americans.

If you don't have the skills to maintain a car, then buying a junker to fix is useless. But, whatever you get, be certain that the teen has performed and will perform, labor in exchange for the car.

My first got a used Hyundai sedan; I took it as down payment on my Chevy wagon from my sister. Daughter's labor? She was my chief babysitter and errand runner with three younger siblings. She had earned it!