Most dealers don't pass on a discount for the reserve, because with most banks the car has to stay with that bank for a minimum of 6 months for the dealer to get that money. If its re-financed or payed off before 6 months the dealer losses that money.
If I sell a vehicle knowing that person won't refi or pay it off, and it takes me to knock off 100-300 more to earn the deal because they will finance with me I do.