Here in the EU, splitting and filtering is legal, done and expected. Cars almost always give you a little space, and my Supertenere fits thru most gaps without an issue. One thing to make sure about filtering: shoulder check before you get in the gap, or you might get plowed by the bike filtering behind you!!
To put how great filtering is into perspective for those who are opposed to it, I have a lot of business in Budapest (but live about 3 hours away)... At rush hour on a monday, I can get from one side of Bpest to the other in a half hour on the Tenere. In my car, the same trip has taken over four hours. That was the last time I ever brought a cage into that town!
2011 Yamaha Super Tenere
2004 Kawasaki KLE
1977 VW Westy camper bus
1976 feet (no titanium yet!)