While Diesel Exhaust Fluid will be easy to find by 2009 for cars and light-trucks, and by 2010 for commercial vehicles and heavy-duty trucks, it is also worth noting that a little Diesel Exhaust Fluid goes a long way.
Driving Range for Diesel Exhaust Fluid Supply in Heavy-Duty Trucks

Some companies say that SCR will take up needed space "back of cab" - leading SCR advocates disagree. In fact, Detroit Diesel developed an evolutionary 1-Box BlueTec SCR system that integrates emissions control technology into one optimized and compact unit. For more information, click here.
[1] Daimler Trucks