Does anyone know what goes under these toy car boides?
 

Only $75 seems like a deal if I can find whatever it is they are supposed to sit on. I suppose short of making something on my own. Maybe a go cart for the kid.

Porsche 911 Pedal Car Bodies Wheels Seats Whale Tails

They are also on ebay...so better hurry if you want them:
Porsche 911 Turbo Carrera Pedal Cars with Whale Tales Seats and Wheels | eBay

It looks like it is electric, not pedal...like this one:
1970s Nice Ride Car Toy Metal Porsche Battery Electric Automatic for Repair | eBay

You could buy a cheap but decent (steel framed) second hand pedal car and go from there.

I can't imagine the dimensions varying much in pedal cars but I would buy the body's first and take measurements before you go shopping.
Locally unwanted kids toys generally go cheap.

Maybe you could cannibalize what you need from one of these (if you want the vintage 911 look:
Porsche 918 Style Kids 12V Electric Powered Wheels Ride on Car RC Remote Yellow | eBay

I'd think if you just wanted pedal cars it would be easy to fabricate the frames...

Or get a peddle car and put a lawn mower engine in the back. That way it goes like a real 911.

I'm not even gonna show my Son this thread!