Weird thing happened yesterday, went to New Hampshire to pick up a motorcycle for my friend. Filled up at an "off brand" station where diesel was about 20 cents a gallon cheaper than most stations. It took 22 gallons and hand calculated was about 31.8 mpg, pretty normal for my truck. On the 200 mile trip home, couldn't get the EVIC to read over 30 mpg, mostly hung around 29.8. Today, went to the local Shell station, topped off the tank and added 8 oz of Hot Shot's Diesel Extreme. wow, suddenly, EVIC has been showing 34 mpg for around 100 miles. Normally I use Opti Lube XPD, I forgot to bring with me to NH, so no additive when I filled up yesterday. Starting to think the additives do add mpgs!