Ford Diesel Van

[questionful]

Hello. I got a job driving a ~100mile daily delivery route with a 2005 Ford E-350 6.0L Turbodiesel. I want to drive more efficiently.

Does anyone know where I can find a graph that shows the engine's efficiency at different RPM's?

I figure that, at 600 miles/week, buying a more efficient car might be profitable; getting 30mpg instead of 15mpg would save $320/month (@$4/g), enough to pay for a new car!

However, as long as the company is asking me to drive this van, I want to do it as efficiently as possible.

Any tips? I already drive efficiently, keeping red lights in mind and trying not to accelerate only to burn on the breaks. I get into top gear to cruise 55mph on the freeway. I pumped up the tires a bit.

Also, where can I find info on how well this engine can take biodiesel?