Significant difference in IS350 fuel economy between 60 and 70 MPH
06-10-08, 06:32 AM
#32
ive never seen a significant change in mpg when the AC was on or off. For 5 years when I had my prelude my mpg was the same in the summer as it was in the winter, both obviously having different usages of A/C. Nor do I see any major difference in my IS. In larger displacement engines the loss from the AC being run is even less apparent than on a low displacement 4 cylinder.
At 80mph I can get around 27 mpg according to the current MPG gauge, 60-70 its around 30-33 mpg. I dont use cruise control
At 80mph I can get around 27 mpg according to the current MPG gauge, 60-70 its around 30-33 mpg. I dont use cruise control
06-11-08, 07:53 AM
#34
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^^^ If the manual says that Snow mode retards timing and is less efficient, then it's wrong. I've done lots of testing to shows that the only differrence to the engine between the modes is throttle sensitivity. At full throttle, the engine performs identically in all three modes. It has also been well documented on this site that snow mode gives better fuel economy in stop and go traffic. However, I forgot to mention that snow mode is always used when I do my 60 MPH tests.
From a roll, depending what speed I am going, if i punched the gas pedal (WOT), there can be this huge delay / slow down in rpm climbing.. I was actually suprised on how much power was cut down..
I had the pedal burried and I could of had a sip of hot coffee waiting for the needle to reach red line..
Did the same test with normal & power modes and the difference is night & day on rpm accelaration and response.. Again this was from a roll not stand still..
Joe Z
06-11-08, 08:06 AM
#35
^^^ I'm certain that this is due to the transmission NOT downshifting, and NOT because the engine is making less power. I have verified this over and over again using dynos and accelleration data via CAN bus on the street. I promise, the engine makes exactly the same power in all modes.
06-11-08, 08:38 AM
#36
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^^^ I'm certain that this is due to the transmission NOT downshifting, and NOT because the engine is making less power. I have verified this over and over again using dynos and accelleration data via CAN bus on the street. I promise, the engine makes exactly the same power in all modes.
I agree the no downshifting may have played a roll.. I also agree the engine is making the same power.. But my experience was that the rpm climb was restricted significantly compared to reg & pwr mode. As if the throttle flap did not open all the way, even though I had the pedal buried..
Jz
06-11-08, 09:10 AM
#37
It does feel slower by the seat of my pants, but when I datalogged the speed versus time (via CAN bus) in 3rd gear for all 3 ECT modes, the plots were identical in the RPM ranges they share. Same was true when I dyno'ed in Snow and PWR. This is why all dyno testing should be done in ECT Snow mode to allow testing at a much wider RPM range.
06-11-08, 12:40 PM
#38
Pole Position
^^ IME, all three modes work exactly alike at WOT. The only difference I can see is that in snow mode, the rear tires will not break loose when launched. Other than that, they feel exactly the same.
06-11-08, 03:03 PM
#42
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This shot is real world, real time, between Seligman, AZ and Moriarty NM. It would have been a perfect run had I not been slowed dramatically by traffic. I measured 29.197 mpg (indicated 28.4) on that leg of the trip, but average speed dropped to 59 mph because I crawled through one lane of traffic for 47 miles behind a line of cars.
I tried setting the cruise control to 60 mph on one of my trips from Sacramento to the East Bay. I had LOTS of data from these trips - 106 miles from home to Union City. I'd drive from the house to the Shell station 5 miles away, stop and fill up (car still warm), then get directly on the freeway, set my cruise, and change speed as little as possible for the entire trip. I never broke 29 mpg no matter what speed I drove. Typical with summer gas was 27.x and 25.x with winter gas. Part of the problem was California fuel and the high level of oxygenates, but regardless, the only time I saw over 30 mpg was on a trip from California to New Mexico after I got all the Cali fuel out of the system, and I still saw 30+ at 80 mph.
Yesterday I drove back from Tennessee (Nashville to Atlanta - 254 miles) with the cruise stuck on 75 almost all the way and saw as high as 28.2 on the indicated with 27.6 by the time I pulled into the driveway. On the trip to Nashville, I got 26.83 calculated but indicated 26.2 when I filled up for the return trip. This was much closer to 80 mph than the return trip was.
06-11-08, 03:23 PM
#43
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I drive about 200 miles a da, Norman, OK to Ardmore, OK. Its all along I35 and I go anywhere from 80 to 90 mph and get around 25 mpg. Maybe I should slow down and get a couple extra mpgs.
06-11-08, 04:33 PM
#45
Huh? Considering my results, it is very surprising that there would be a 6 MPG drop from 60 MPH to 70 MPH, and only a 3 MPG drop from 70 MPH to 80 MPH. Of course, my results have no resemblance to yours. I've never had a problem getting 35+ MPG at 60 MPH.