My understanding is that some, if not most, Mirai purchases are for testing fleets. Before there were any commercially produced fuel cell cars such as the Mirai, those government agencies and research groups that ran FCEVs had to make them (or pay someone else to make them) as conversion vehicles, or at least that's my understanding. There were about two dozen non-public H2 dispensing stations in the U.S. before the California Fuel Cell Partnership affiliates started building them in California, and that suggests about the same number of agencies and research groups running (small) fleets of fuel cell cars. These days, those fleets are probably getting their cars from Toyota, Honda, or some other source. So fleet sales may explain why there seems to be a lot of month-to-month variation in sales of FCEVs. Now, what I don't understand is why there are still dozens of gov't agencies and/or privately funded research groups still throwing money away on testing hydrogen-powered fuel cell vehicles. You'd have thought that this was an experiment that had run its course decades ago. What more can there possibly be to learn there? There may be a future for FCEVs, if they can use some fuel other than compressed hydrogen. That is, if they can run on a practical fuel. So there might be a reason to continue research along that line. But it seems to me that spending money on testing or development of hydrogen-powered FCEVs is just throwing good money after bad.