It is illegal to use a window suction cup for your gps - as many have stated already - but I've seen so many people doing it I'm not sure how energetically it is enforced. Of course, I wouldn't want to be the one the cops choose!

For me, I've always used the bean bag type dashboard mount. It just sits on the dashboard and holds the gps firmly in place. Plus, I can easily tuck the entire unit (gps and bean bag mount) below the console and out of sight when I exit my car. No tell-tale signs!

Thanks,Fodorites.
I am now the proud owner of a nav-mat bean bag holder.

Lots of great info, thanks for asking - and on the lighter side .. as to whether you "can" or not...
My mother was well known for correcting grammar and when she was pulled over by a motorcycle traffic cop at a speed trap in Seattle once (I was a passenger) the cop said to her, "You can't go that fast here. The speed limit is 25." My mother replied, "You mean I MAY not go that fast here."
She got the ticket anyway.

I just came back from four days in Sonoma. I used my GPS..stuck to my windshield. Saw plenty of policemen and a Hell of a lot of people yakking on their cellphones while driving...if ythey are "enforcing" any of these laws it wasn't apparent.

suz, as someone who is always yelling "ly" at the TV, I LOL at your mother's "talking to" to the policeman!

Dukey, the cell phone law isn't yet in effect (goes into effect July 1st). The suction cup law is already in effect and while I'm sure plenty of people get away with violating that law (and so many others), I wouldn't personally want to be the one who gets a ticket for a violation!

It is not a "suction cup" law. The section prohibits anything placed in/on the vehicle that will obstruct the view of the driver.

So decals (except for lower two corners of windshield and rear window passanger side, no more than 7 inches square) are a no, no. Anything on the dash or rear deck are also a no, no.

There is also an exemption for a small area in the top center of the windshield for a traffic warning device receiver. I am not sure, but reading the description in the California Vehicle Code (26708) if you had one of those GPS devices that also gave you real time traffic that might work for that location.

Does this get enforced? Probably not very often unless you get stopped for something else or look like you "don't belong" in what ever area you might be hanging out.

My bigger concern would be if I got in a crash with somebody and the officer noted that my vision was obstructed by something on the windshield or dash.

When we bought my MIL a new car in 2006, it came with satellite radio and the receiver is attached to the windshield at the upper edge just to the right of the rearview mirror. It's a relatively large triangular "box" about 2" long on each side. I find it distracting, but I don't think it obstructs a driver's view of traffic. After this discussion, I don't know whether this device is legal or not.