Guys,
I just had to take a quick run out of town on bidness. A last minute, "hey go check this" kind of thing.
I had to go to SPARTA-nburg, SC. Great place. That whole Greenville to Spartanburg region. Great people, great area, very unAtlanta. No skunky smell of "diversity" everywhere you go, like in Atlanta. Anywho...
I had about 75 miles on the tank already and took off to Spartanburg Tuesday evening, after the Atlanta road wars on the Watermelon 500 had mostly subsided. And cruised my way on up there. No A/C, just put the windows down. Was very comfortable.
It's just under 200 miles to there. Then Wednesday (yesterday) I decided to juice it up on my way out of town. I got 45.952 mpg on that tank to get up there. I left there about 1 pm, and it was quite warm. So I decided I would do an all-interstate cruise with the A/C on and refill it near my house just to see what the cute little bad-ass tow rig Blueberry would do with the A/C on.
It got 48.7 mpg on the way back, with the A/C on. That's to the first click off of the fuel pump. In reality, I'm going to bet it was in the 47's for true mpg. But in any event, I was AMAZED at the interstate mpg.
Here's what I did different than I had ever done before. This forum has clarified that at ~3,500 rpm is where the (big time) MIVEC system starts MIVEC'ing. As I understand, it is just intake-side valve timing. I don't know if it opens sooner, opens later, or both. So I slapped in my ELM 327 and ran the (free) torque light app, and set my Cruise control at 3,475 rpm. That's just barely skimming 69 mph. I did this both on the way there and on the way back.
Watching the app, the rpm would run 3,475 ± 75 rpm or so. So yes, it would run up and into 3,500 rpm. However, when it would run into the 3,500+ rpm zone, it would back off the throttle in order to try to achieve the set speed at 3,475 rpm. So even if it MIVEC'd even a skosh over 3,500 rpm, it was off-throttle MIVECing. So I summized MIVEC was having little to no negative effect on mpg in those off-throttle 3,500+ rpm events.
I guess this is applicable to mainly the 5-speed guys. As I would imagine the rpm would be all over the place with a CVT. Especially on this run. That run down from Greenville back to the GA state line was very much UP-DOWN-UP-DOWN-UP-DOWN. Same in GA, just less steep and less compressed with the up-downs.
On the speedometer, let me explain where to set the cruise (if anyone is interested ... (crickets, crickets, crickets)). If you can exactly center the gauge on the 70 mph mark, and then juuuuust barely skew it off ever so slightly off-center of that 70 mph mark to the right, and set it there ... that's where it was on my guage hitting 3,475 rpm through the app. I'm going to guess that numbers on the app were more accurate than the tachometer. I didn't pay much attention to the tachometer. It was close to the same rpm anyway.
Many have said, the Mirage is not a good interstate car. I do see their point. However, if you can sit comfortably in the car, and have the discipline to roll along at 69 mph, set the tach as described above, run the A/C as necessary, and KNOCK OUT some especially good fuel economy! Ohio and Kentucky used to have maximum speeds of 65 mph (don't know what it is today). And SC had a max speed of 65 mph where I was. So 69 mph wasn't too far behind the average, and was quite a comfortable cruise.