At time of purchase in 2004: 2001 330i $3000 down, $429/mo. for 42 months at 3.4%.
At time of purchase in 2006: 2004 X3 $6000 down, $400/mo. for 48 months
Trick is buying a NICE CPO with less than 10K miles/year and paying off loan early before trading it in. This avoids the severe depreciation after 80K miles (or 8 years of age) and allows you to buy a $50,000 car for half the price.
If you can't afford to maintain your BMW, get rid of it!