A while back, I mentioned about the Argonne Green Transportation event. It displayed several hybrid and hydrogen vehicles that supposedly have better millage and/or very little polluting emission. The star of that event were a number of BMW vehicles that ran on hydrogen.
These cars have been tested at Argonne, and it appears that it is the only public facility that can test vehicles with that low amount of emission. The testing project has now been summarized on video that's available on YouTube.