Nice car, but that doesn't mean you shouldn't use your blinkers.
You should also avoid randomly slamming on your brakes with no warning to let cars coming out of a driveway go and gesture them to go when there's still incoming traffic.
I wish it was just a BMW thing, but it's not. I've noticed that the use of the turn signals is in inverse proportion to the cost of the car; the more the car costs, the less the driver uses the turn signals. This seems especially true if the car is worth more than $40,000 USD.
Nice car, but that doesn't mean you shouldn't use your blinkers.
You should also avoid randomly slamming on your brakes with no warning to let cars coming out of a driveway go and gesture them to go when there's still incoming traffic.