Just purchased a 2003 BMW 330XI and previous owner said he only used regular 87 Octone gasoline and the car runs fine with no pinging. Is this ok or should I use premium unleaded ?

You don't HAVE to put premium fuel in your car, but the maunfacturer's specifications call for it. Therefore, you will get the OPTIMAL power and OPTIMAL fuel efficiency if you follow factory specifications. Premium fuel really isn't that much more expensive. For a regular fuel cost of $2.51 and a 15gal tank its $37.65 to fill up. For premium cost of $2.74 it's $41.10 to fill up. $3.45 a tank is an EXTREMELY small price to pay for better fuel efficiency and power. Besides the better MPG will make up for the rise in price.

Always use the correct fuel. You are damaging the engine and I wouldn't have purchased the car from someone who admitted this. Don't take advice from GM and Honda owners. The car was designed for 91 octane and needs it. Otherwise you will be on this board later asking about why your car runs rough and blows black smoke.