Agree about the silver is a bit boring, my last car was silver, I am most likely never getting another silver car. Get the 545i, but just find one in a different color.

 

All else being equal (transmission, sport package or not, major options, etc) I would go with the 545. However, since you plan to keep it a long time, the total cost for the 530 should be significantly less considering gas and service. For gas alone I calculated around $1000 more a year for the miles I drive with current gas prices. Wish I had the power of a 545 though (it would be worth the extra cost to me).

 

In the long run, the I6 may be more reliable and cheaper to repair than the V8.
The I6 will get much better fuel economy.
But the V8 power makes a BIG difference.