non-custom cars are the one which are smuggled from other countries and the taxes and duties arent paid on them ... its crime to have a non-custom car ... and custom paid car means opposite of non-custom ... auction cars are like old govt jeeps,trucks and other vehicals of govt that are of no further use of them so instead of disposing them they sell them via auction ... than other auction cars are of banks and insurance companies that are of the people who dont pay the installments for there leased cars to bank so the bank get those cars back and sell them in auction so they can get there money back.. hope u got some idea