Why does the Government subsidies Car Manufacturers

[dogfish]

I was thinking the other day why does the Government subsidies the car manufacturer directly?
Why not subsidies the person/Individual purchasing a new Australian manufactured car instead of the vehicle manufacturer itself.
Would this not encourage more people to buy Australian made vehicles and we as purchasers get better bang for buck especially if you got say for arguements sake a 15/20% subsidie off of the new price instead of buying the optioned up Falcon you might want to spend the same amount of money as you originally intended and buy an XR6 or something instead.
I am talking about locally made vehicles only.
I also believe this would work better for all concerned including the Ford V's Holden battle with technology and performance being the biggest winner of all.