EML, (!), and brake light come on while I'm driving about 45 mph (not sure if this is just a strange coincidence.) Lights are yellow (means car is not getting ready to explode) and after referring to the manual, found out that it cuts engine power by 50%. Car is noticeably harder to accelerate. BMW dealership said it was probably an electrical problem. Before spending big $$, I would appreciate some professional opinions! Thanks

EML light coming on (which does NOT mean You've Got Mail) actually stands for Electronic Motor Load regulation. It basically tells you the car is on what is commonly called "emergency limp back mode". Power is cut to prevent damage to the car. It's BMW's equivalent of "safe mode" on your PC.

This could be caused by a number of reasons including but not limited to:

Catalytic converter failure
Coil failure
Throttle position sensor
Some other sensor failure

The easiest way to get an idea on what's going on is to go to Autozone and get a free OBD-II reading off the car.