Pete, are you serious? CNG buses have no odor? Of course they have exhaust fumes, and yes, you can smell them. Just stand at any bus stop as a bus passes by. They are not nearly as intolerable as the old diesel buses, and I am very glad they replaced most of the fleet with CNG vehicles, but to call them odor-free is waaaay over the line.
Now to the bus lane. I have not seen the proposal. If this just a lane painted on the road at each curbside, then I would not be in favor of this. (By the way, it has to be TWO lanes, one in each direction, otherwise it's pointless.)
If this is a fully-separated, curbed lane in the middle of Wilshire, with "stations" for people to wait at (that is, no way for cars to wander into the bus lane) then it's a much better idea. I guess this amounts to nearly true BRT, except the buses do have to wait at traffic lights.
As far as bus bunching, this could be calmed a bit if the 720 and 920 only ran in the bus lane, and the 20 (local) ran in mixed traffic with all the other cars. This is only sensible way to run those routes. My two cents.