 Some things to look out for if you're looking for a used 2003 audi A4: Audis are known for guzzling oil and this car is no exception. If you are buying a used car you may need to flush out the heater core. It has a flaw where it will accumulate gunk over the years and the heat will not work until it is flushed. Also ask about how recently the timing belt has been replaced. If yours snaps, the "interference engine is toast.