Anyone reading about the Los Angeles Motor Show, or even being fortunate enough to visit, could not have failed to notice the interest in hydrogen as a fuel. Toyota unveiled the Mirai, a hydrogen powered, medium sized car being introduced in California in 2015, while Audi showed off the A7 h-tron, a plug-in hybrid with a battery-only range of 15 to 20 miles before switching to the hydrogen powered fuel cell. VW, Hyundai and Honda either had cars on their stands or spoke of their plans to support hydrogen powered cars in California.   The key to success is going to be an adequate hydrogen fuelling infrastructure. To this end, Honda and other manufacturers are helping to fund the infrastructure in Southern California. Could this become the automotive technology of the 21^st century? We discuss this in “Part 3- Technology” of our new eBook that is free to download from the museum website.