what motor does that excursion have? when it comes to diesel they arent all the same. i mean far from it. when it comes to the motors that ford uses. you have the 7.3 turbo, 6.0, and the 6.4. now they are running a new motor. havent any info on that yet. but one of my best customers is looking for info so i will soon. as for the other navistar engines. the 7.3 will always kill the other in fuel economy. the other 2 the 6.0 and 6.4. you will be lucky to get in the teens. it hasnt proven to be a good motor in anyway but power. but reliable fuel minded i know it is not. the vw tdi is such a good motor. power to weight ratio is just almost 100% perfect. really no competition. what moter do you have in the ford?