What is the fuel tank capacity of a Sterling over-the-road truck and how far can it travel on its two tanks of diesal?

The fuel capacity is whatever size tanks the customer orders. Long distance line haul tractors are typically ordered with dual 100 - 200 gallon fuel tanks. You can expect fuel mileage to average between six and eight miles per gallon, depending on factors including weight, road conditions and terrain, etc. The Mercedes-Benz MBE motors are supposed to be the most fuel efficient option on the Sterling.

By the way, if you wanted to buy a Sterling built-to-order, I'm afraid you're a bit late - Daimler A.G. shut down the Sterling line this past Summer. Sterling trucks were a bit more commonplace in daycab and straight truck applications, so you might encounter a bit of difficulty trying to find a used sleeper berth tractor with specifications which you want.