See if there is a way to rent one for an entire week. Or trade with a friend who owns one for a week. THEN ask yourself if it's worth the 15k. The reason I say a week is because that will take you through a real life work week and weekend. I wish I did that when I bought a 530i a few years ago. The test drive got me hooked. Bought it and I was bored 3 days into driving it. I sold it a month later.
2010 335i AW e90 Msport