ObD

GPS knows your location and thus knows what time zone you're in. Probably ten lines of software code which would double the cost of Nav.

Rudy

Well obviously they don't -- the GPS system only sends a Coordinated Universal Time (UTC) signal. It's up to the receiving device to adjust the UTC signal for time zones and/or DST changes.

Mercedes does it, heck my Honda does it as well -- except for the fact that they have the wrong DST dates hard coded into the car so the automatic DST doesn't work anymore. When I asked the Honda service guy about a software update to fix that problem, he looked at me as if I was from Mars! Even funnier, the service guy, just to be sure, asked the "Honda certified mechanic" if he was familiar with what I was talking about and the mechanic told me that the car gets it's time from the satellites and the satellites are wrong!! After I explained to him that the satellites are not wrong, I started to see some smoke coming from the guy's ears so I decided it was not worth my time arguing with the dude...

On cars that do have the clocks set by the GPS system, things work out really well. The time even changes instantly as you cross a time zone, etc. I see no reason why BMW decided not to implement this technology in our cars.