What works? Showing inventory with no pricing until form fill unlocks instantly OR don't show inventory at all until form is filled and then show instantly OR don't show inventory even after form fill but shopper has to receive email to unlock inventory and price?These work, it's usually an internal fight among dealership ownership/management. I've seen conversions over 20% on these with impressive sales numbers too.
All that matters is what you show/do after the fact. People forget they had to go through a squeeze page really quick.