Some of you might remember the other thread at the bottom. 27.4 mpg was my previous best for a similar drive and weight. After adding a 16.3:1 afr lean cruise and aggressive DFCO parameters I was able to average 30.1 (pen and paper) over a 500 mile drive (single tank of gas!) from MA to PA. The engine is a 5.7L LS6, used in the previous gen Z06 Corvette. It has a custom grind cam, headers, larger hand ported throttle body and intake manifold. The engine makes around 470 horsepower at the crank. Factory 3.73 gears
and a 6 speed with overdrive being .57. Another thing I changed was the oil. I was running Pennzoil Ultra 5w30 previously but I changed to non petroleum based G-Oil 5w30. The Caddy seems to really like the G-oil.
Now the car was loaded up for this trip, trunk was jam packed full of luggage, drinks, electronics, food, emergency tool box, coolant, oil, duct tape. Backseat was also full almost to the head rests. Then I had my girlfriend in the passenger seat. I could tell the car was struggling with the extra weight, on a flat surface empty I can show 39/41 at cruise on my readout. I was struggling to show 35. Thanks to the coach buses on the highway I was able to avoid alot of wind resistance. I didn't do any pulse and glide, just light foot driving. Highway speeds were fast to keep up with buses 70+ almost the whole way. Early in the trip I did some EOC coming up to red lights.
I got the best MPG on the trip back. On the way up I average 28.8 but I sat in a half hour of slow traffic around NYC. I also paired off with an M5 and a later on a new 911. I was still happy with the average though.
http://ecomodder.com/forum/showthrea...mpg-22967.html