This post is a follow up from the previous blog regarding my fuel mileage while using a cruise speed of 55 mph. I left off arriving in Laredo, TX with a dash indicated 12.4 mpg for 884 miles since leaving Meridian, Mississippi. I also noted that my truck had not yet completed a passive regen. The regen takes place approximately every 1,400 miles and usually pulls down the average fuel mileage.
I arrived in Laredo, TX which required some in town driving in order to complete my unload and reload of shipments. At that time the dashboard display read 12.1 mpg. I left Laredo and headed back to Charlotte, NC. My route took me through San Antonio, Houston and ended in Egan, LA. I encountered cross/head winds the majority of the trip. A passive regen was completed as I crossed I-10 and the GVW was approximately 68,000 lbs. Upon arrival in Egan, LA the dashboard displayed an 11.4 average mpg. I stayed in Egan for the night. Before shutting the engine down , I made a meal by microwave for 7 minutes, maneuvered into a parking spot and finally turned the truck off. In the morning, I awoke and conducted my pre-trip inspection and headed for Meridian, MS where the truck would be refueled for the first time since beginning this test. In the morning hours, as I began my trip onto I-10 in Egan, MS, the dash read 11.3 mpg. I continued across Louisiana and turned north towards Meridian, MS. At this point, the dashboard indicator had crept up to 11.4 mpg. Now, I’m on my final leg prior to refueling the truck for this trip and I’m anxiously awaiting the results of the “real numbers” at the pump. The route to Meridian, MS from Slidell is uphill on average and therefore it pulled the dashboard indicator down to 11.2 mpg. I made my way into the travel center fuel island to refuel the truck.
The results are as follows:
After traveling 1,773 miles @ 55 mph – 164.347 gallons of #2 ULSD fuel was pumped into the tanks of the Cascadia Evolution for an end result of 10.78 mpg. This figure was a bit farther from the dashboard figure than normal. While pumping the fuel, a person came over and began to chat with me. I believe this resulted in my filling the fuel tanks a little closer to the top. I did a little math to determine how many gallons it would have been figuring at 11.2. The figure was 158.303 which is 6.044 gallons less or only 3 gallons per tank. We all know how easy it can be to fit 3 extra gallons in a 120 gallon tank.
After refueling, my next destination was Charlotte, NC. My schedule ran such as to not hit rush hour in Atlanta, GA therefore, I decided this would be a good leg to calculate average speed at 55 mph cruise speed. The normal average is 59-61 mph with a cruise setting at 65 wherever applicable. The result ended with an average speed of 54.32 mph.
I truly believe it’s the E-Coast feature of the Detroit DT12 Transmission attributing to such a small loss of average speed.
When I reached Charlotte, NC, the dashboard read an average fuel mileage of 10.5 mpg. I traveled 38 miles to pick up a load prior to arriving home for the weekend.
On Sunday, I headed for Birmingham, AL to drop off my shipment. I encountered torrential rain almost the entire trip and heavy traffic jams for the final 125 miles. This leg was 418 miles and the distance since the last fuel up was 1,139 miles. The dashboard indicator since the last refueling was at 10 mpg. The next day, I unloaded/reloaded in Birmingham, AL and headed for Cleveland, NC. Traffic went well this day. Upon arriving in Cleveland, NC the dashboard indicated 10.4 mpg since refueling 1,585 miles prior. The trip fuel mileage for this day was 11.7 mpg for 456 miles.
In Cleveland, I reloaded and headed back to Birmingham, AL to deliver. I stopped in Carnesville, GA to refuel. The dashboard was indicating 10.6 mpg. After traveling 1,811 miles since last refueling in Meridian, MS. I put 170.751 gallons of fuel into the tank which figured to 10.606 mpg .I finished the
trip to Birmingham, AL with a dashboard indication of 11.9 mpg.
I’m going to continue testing at the 55 mph cruise speed. Stay tuned and I’ll be writing about my findings in a few weeks .I’ll be working on calculating the numbers to see how well the cruise speed of 55 mph fits my current business model.
One thing that has changed my thoughts on selecting a cruise speed would have to be the E-Coast mode on the Detroit DT12 Transmission. A large portion of the time, the E-Coast function allows me to be above my cruise control speed setting. My new way to view this would be that with the DT12, I am now only powering/fueling the truck to 55 mph… everything else is a bonus!