Tell him where to stick it.
If you buy a moped-priced car, within five years you'll put triple or more that amount into it via parts and labor, cause it won't hang in there, and will break down repeatedly...at the worst possible times, and then ya have towing charges too.
That is...if it even lasts five years, which it won't, more than likely.
Then there's insurance, which for you, being 18 and a new driver, you might as well just slit yer wrists and pour your blood on the counter, for what they'll want to charge you.
Registration, Inspection, Emissions, Tags, etc...FORGET it.
Unless you like working 90-hour workweeks, do not expect to be able to afford both a car and important stuff like Rent, Food, and Bills at the same time - I've been down that route, and hated every second of it.
Having a moped has allowed me complete financial freedom since I was 17, and I am 30-some now and made a good deal of money....driving a cab (ain't THAT a laffer, me gettin paid to drive a car!), which solves any residual transportation problem quite nicely, thanks.
Mopeds are not dangerous, what's dangerous is morons in their own little world, on their cellphones, whatever, in cars, because it so isolates them from what they're doing that they don't pay attention - and you stand a far better chance of dodging THOSE morons on a moped than in a car.
Mopeds are not expensive in that YOU can do most of your own maintainence and repair, armed with Fred's guide and the knowledge you can find here, and for the mileage they last and the fuel they use, are the cost effective alternative.
As far as moving stuff goes, well, geewhiz....if I have to move my household, U-haul will rent me a truck for $20, whee, some big investment there <sarcasm>
If I wanna go visit the east coast, I can get an unlimited mileage rental car for $112 for a friggin WEEK, and at that cost, why the hell do I have to own one save as a keep-up-with-the-jones's 'status symbol' ?
My Roomie kind of regrets buying a car, being that her car is worth only $5,135 and she still owes about $12,651 on it...you tell me that's a good 'investment' ?
I paid $450 for my moped, and it's current "blue book" value is over $700 in it's now-reconditioned shape.
The car I had, and was paying for...that lead to 90-hour workweeks to support it ? I traded it FOR a moped, and feel that was the best damn decision I ever made.
Your vehicle is supposed to support YOU, not the other way around, if I wanna support something with that kind of money, I'll have kids.
Don't expect parental figures to listen to reason on this issue, however...I wound up with that car being forced on me by an aunt, with the aforementioned results, and I've been on open-warfare terms with her ever since.
They have thier little status-quo perception of the world, and will stick to it, no matter how bad it hurts, and even when it's obviously wrong....it's the way they were socially "conditioned" by their parents, and the way they'd like to socially "condition" you - situation as you explained it being a prime example.
With some of us it just doesn't take, common sense tends to be difficult to rub out in some of us, as it were.
Do not expect him to agree with you, but with luck you can maybe get him to respect your decision, your life, and how YOU feel about it, as long as you grant him the same respect in return.
Simple enough ?