There are 230 million cars and light trucks in the United States, over 8 million Class 8 Diesel tractors (the front part of an 18-wheeler), and a half a million school buses. Over 80% of these could be modified for hydrogen use.

Diesel engines are classified as compression ignition engines, since the heat and pressure of the compression stroke is what ignites their air/fuel mixture. Asemblon plans to offer products that would provide a 10% addition of hydrogen to boost performance and to reduce emissions. Another product would provide 30% hydrogen to displace more of the diesel fuel to further lower emissions. Without major modifications, a 50% replacement is seen as the current upper limit for diesel use.

Spark ignition vehicles (most car and light trucks on the highway today) are easier to modify, since the timing of the ignition spark relative to the engine rotation can be controlled. Initially, these engines would be boosted with hydrogen, but ultimately hydrogen would replace 100% of their fuel.