A thread here perked my interest about the criteria used to allow vehicles to use the HOV lane. For those of us in urban areas, the prospect of HOV lane use is pretty enticing. As it turns out there are two qualifying categories here in California. (Go ahead and get your California heckles out; but, "as goes California, so goes the nation", or so the saying goes. While the HOV thing is also in large part driven by the Department of Transportation, these agencies cross reference each other's legislation. California is inevitably included because of the standards set by the California Air Resources Board.)
Anyway, the first is for alternative fuels (like natural gas) that qualify as both inherently low emission vehicles (ILEV) and as super low emissions vehicles (SULEV). Oddly enough, there are a lot of vehicles which meet this criteria but the Honda Civic GX is probably the only one available to the public in limited states.
The second category is for alternative fuel or gasoline hybrid vehicles which have a highway mileage rating of 45 mpg and qualify as a advanced technology partial zero emissions vehicle (AT-PZEV), super ultra low emissions vehicle (SULEV), or ultra low emissions vehicle (ULEV). There are catches here. It looks like ULEV vehicles qualified in 2004 if the mileage was above 45 mpg.
Although it talks about "hybrid" vehicles, it is hard to know how they qualify that (i.e., must it be partially driven by electric motors?), I'm guessing the more important thing is whether it qualifies for AT-PZEV vehicle emissions and this seems to be the criteria for current cars meeting the requirement.
Coming in at tier 2, bin 5 the Fortwo qualifies as ULEV vehicle. It's 2008 EPA highway mileage is slightly inadequate (41 mpg hwy), even though it came in at 45 in 2007. So, from what I can tell, it looks like the Fortwo will not qualify on either the mileage or emissions count.
They sure are close though. AutoCar suggests that the "mini hybrid drive" (on-off engine thing) improves the Fortwo's mileage by 6%. Depending upon rounding, that should put the Fortwo close to the 44 mpg highway mark. That's close enough to taunt the heck out of engineers and I'm betting they'll figure out how to get it there. The question then would be to see whether MHD would also bump up the emissions rating of the car to AT-PZEV. It is hard to imagine what "partial zero emissions" means unless there are electric motors. I doubt a car without emissions when sitting would qualify.
I think there are a lot of people driving a Prius or Civic Hybrid for the HOV access alone. Stoicism aside, I think the Smart would be a most welcome alternative.