Is it true that if i want to buy a brandnew car,the dealer will ask for 4 crdt crd companys(AMEX,MC,DICVR,VSA)

Not true, they will ask you about your credit, and for permission to pull a credit report to determine your credit worthyness, this determines your rates, and payment. Great credit, less payment, lower interest rates, better perks. Simple as that. Good credit is so important.