Bob's 2011 Malibu LTZ V6
Saturday the 17th I started my trip from Louisville, KY, to Alexandria, VA, at 9:40 AM and held myself to 60 MPH the whole time. As I drove I kept tabs on the avg mpg on the DIC (driver info center). It climbed past 28, then 29 and finally to 30 when I put the display back to temp and odometer. When I checked it again it was at 32.x and then it got to 33. I was hoping it would get to around 36 (like my black '09 V6 could) but it never got past 33.9. After it got that high I got into some steep hills that dropped it to 32.x (scarey!), where it stayed for a long time. After I got to the flat lands it started creeping up slowly. I had already gotten past 400 miles and it looked like I was going to be able to make it all the way to my destination on one tank, but with the avg hanging around 33.3 the computer kept showing I was about 50 miles short (Garmin GPS showing distance to destination). Earlier it looked even worse -90 miles- and then actually got to the point that it said I had more miles to empty (MTE) than I had to my destination! But alas, it was not to be. My DIC reported 68 MTE, then 63, yet I still had 115 miles to go. Then it said "Low Fuel" and the MTE changed to a similar message. (Can't remember exact words right now... dang CRS!!) I was working hard to trust my MTE calculation as I approached 500 miles since the last fill up that morning, and though it was arbitrary I wanted to get past 500 before filling just to prove I could. And I did! I passed a gas station at 498 and started sweating a little, but at 503.5 I found a Shell station and started breathing again. After getting to my destination and settling down I did the manual calculation on the mileage. The DIC reported 33.6 when I stopped to fill, and the manual calculation yielded 34.486!!! I drove all the way from Louisville, KY, to Edinburg, VA, without stopping or fueling, a distance of 503.5 miles on 14.600 gallons, paying $50.50 at $3.459 per gallon of 89 octane (yeah, it clicked off a little before that but I topped off about another 30¢ or so). As a matter of fact, I didn't have any snacks or drinks with me (very unusual!) and just never felt the need to stop. It was straight through from 9:40 to 5:55, a drive of 8.25 hours without a break! Of course I tinkled and got a mocha drink at the Shell pit stop and then hit the road again, only this time I cranked it up to 70 to get where I was going, which was only another 50 miles.
I figure that 500 miles at an average of 60 mph = 8.33 hours, whereas if I had been driving at 70 when it allowed (and probably more like 75) it would have a slightly higher average of 66 mph (rough guess), yielding a trip of "only" 7.58 hours, or a savings of 45 minutes, but at a cost of about 7 mpg and maybe more, since I seem to usually get around 27.5 on trips. So, at that mpg it would have taken 18.3 gallons for the same distance, or 3.7 gallons more. At the price of $3.459 that means I saved $12.80 and paid myself $17 per hour for that 45-minute loss. I just might make the return trip at 60 as well!