When you buy a new car, what percentage do you put down as a down payment ? ?

The more you put down, the less you pay in interest so I suggest you put down as much as you comfortably can afford...

100% never a borrower or a lender be

No single answer but you're best putting down as much as possible to lower your monthly payments.

Never bought a new car. Only financed one car. I put zero down except I paid sales tax and tag out of pocket.

I was able to do that because I bought the car for less than loan value.

None,  I always pay cash. If you can't afford it, don't have it. That's my philosophy. 

Whatever you agree to.  Many have promotions with '0 down', but as most people know, the more down, the better you will be in the long run.

I pay 100% or I don't buy.

I have always put down 100%, that way I avoid finance charges.

As much as I want

as much as i can to lower payments