Do car dealer salesman lose commission if new car end up returned to their lot?

Any sales job with commissions on sales, finance, insurance, maintenance plans works in the same way, whether cars, kitchens, bathrooms, or similar.

Commission is never paid until the deal is done and the finance has been accepted. 

So any deals which get rolled back and cancelled do not produce any commission. 

There have been some situations where the deal appeared to have gone through all the way and I have been paid commission which sometimes were rolled back after that. When that happened I certainly didn’t keep a single cent of those commissions and they would be clawed back from my next payment of wages. 

Spot delivery makes no difference to that: a senior member of the finance team may decide to offer spot delivery, but if the deal has to roll back then nobody gets to claim their commissions.

REPEATED QUESTION REPORTED.

The car sales is not the one that allows spot delivery, the finance person is.

However, since the car never sold, the salesperson would not get commission for it.

Dealer will not pay commission until the sale is finalized. 

Yes. But it could just reduce future commissions if it was already paid as you seen to have this delusion that thousands of cars are spot delivered every year at every dealer.  In reality, it might be 1 a week.  You think you can be hired as a salesman, sell 10 cars in your first day via spot delivery to deadbeats and then you and them all flee the country. And the dealer never thought about that?