Off-road diesel is illegal to use for private vehicles as it is not taxed. Typically, using off-road diesel outside regulations makes one a criminal for the purposeful act of evading that tax. Despite its ability to be used in cars driven on highways and roads, it is still an illegal endeavor. Due to its red coloring, law officials can easily tell the difference between the two. Fines for using off-road diesel in a personal or company vehicle that is being used on the highway can be upwards of $10K. Leave it to Howard Energy to make sure you have the correct type of fuel for your equipment and vehicle fleet.
There is one exception to the rule: off-road diesel is allowed to be used in on-road cars in times of emergencies such as natural disasters.