To calculate your fuel savings, check out this link.
Webasto heaters are up to 33% more efficient than the competitor's. A tractor engine will burn about 1 US gallon of fuel per hour where an air heater burns about a cup. The math is simple. You're saving gallons in an 8-hour period when the rules say the driver is out of hours. In metric terms, in an 8-hour period you would use as little as 2L-3L of fuel rather than 30L of fuel. 28L every 8 hours of idling during a layover adds up quickly! At $1/L that's $28/layover. Assuming 48 weeks a year on the road, with 5 layovers per week, at 8 hours per day, that's over $6700. The heater pays for itself the during first season on fuel savings alone.
Add to that the huge decrease in air pollution created, you're saving the environment and your lungs if you're the one sleeping in the bunk. As the owner of the vehicle, you also save on maintenance costs since your vehicle is not idling, which breaks down engine oil while unnecessarily wearing out engine components and increased DPF maintenance costs. And, you won't get fines for breaking by-laws about idling either! Those large engines are meant to pull heavy loads down the highways, not to substitute as furnaces. They're lousy furnaces, to say the least.
