[header] How to drive a turbo diesel car with manual transmission efficiently [title] Choose the right gas station to trial and stick with it for duration of the steps below. [step] Not all diesel fuels are equal quality. Some are " dirtier " than others, and will negatively affect your mileage. 
Switching stations usually means switching the specific type of diesel fuel, so stay consistent. Find a gas station that offers a low price on diesel fuel, and also offers self service diesel pumps.