There was a $1450 higher MSRP in TrueCar configuration than in the BMW configuration. I determined that TrueCar was adding that sum for the interior Color (Mojave) even tho the Premium package was included. The extra $1450 throws off the whole TrueCar calculation and I assume that following thru to a TrueCar dealer, you'll lose it but I don't know.
On the other hand, bmwconfig.com worked exactly like the BMW configurator and gives you the accurate invoice price that you can print and take to the dealer.
Caveat Emptor.