1. If possible, try to buy your vehicle from a reputable dealer near the end of the year. November, December, and January are the best months to shop for a new vehicle. This time of year, you can negotiate the lowest price possible, because dealers are willing to offer steep discounts on models of cars not sold from the previous year. Dealers need to make room in their inventory for next years models. For example, you will save thousands of dollars if you buy a 2008 model BMW as opposed to a 2009 model. Both vehicles are brand new and never been driven off the lot, but the former represents last year's inventory.
2. Never finance your new car through a bank. If you don't have cash to pay for your BMW, always finance your car through a credit union to get the best interest rate. Credit Unions are not-for-profit organizations that are sponsored by the members, whereas banks are for-profit. So you will always get a better interest rate when you finance your BMW through a credit union. Always shop around at several credit unions to find out the best interest rate for auto loans, because their rates will vary. Don't be afraid to inquire about memberships with any credit union, because the membership requirements are generally very general these days, so just about anyone can now join any credit union without having to worry about any restrictions.
3. Always comparison shop and get several written quotes from several dealers. You can do this online or in person. For example, suppose Jim's BMW Dealer offered you a 2008 7 Series Active Hybrid BMW for $88,000, and this price was already discounted 10% off from the manufacturer sticker price. So you take this quote into their competitor called Sally's BMW Dealer and ask Sally what she can do for you. Sally see's that she doesn't have the same color that you want, but she is willing to discount this even more down to $78,000. Now you take Sally's quote to Ralph's BMW Dealer and show Ralph what Sally is willing to give you and ask Ralph how he can beat the $78,000 price. The key is to keep your emotions in check. Be patient to shop around and not allow anyone to talk you into signing for the car on the same day that you are negotiating. This will allow you to get the dealers to negotiate as low as possible before you commit to buying your new car.
