Diesel has the particulate problem. Though personally, the fact that diesels burn less overall makes them a good candidate. And biodiesel and WVO sweeten the deal.

Hydrogen is always going to be a no-go. The upfront cost of fuel cells or ultra-high pressure hydrogen storage, as well as the HUGE cost of hydrogen production and compression for use in high pressure storage make it a very marginal return... even if you get your hydrogen "free" via solar-power.

Electric cars could become mainstream long before hydrogen due to the huge investment requirements. Manufacturers have been making hydrogen cars for decades. It's actually ont difficult to do so. But it's nowhere near cheap. On the other hand, electrics have gotten to the point where they're only twice the price of gasoline cars. A price point hydrogen will take another few decades to reach.

And in e meantime, hydrogen vehicles will still cost more per kilometer to fuel than electrics or gasoline cars...