This last weeked my wife, myself and my mother-in-law went to visit and have dinner with my daughter. We took my mother-in-laws 1998 Grand Caravan with the 3.8 L , 4200 pound Van. It has a real time mpg guage with fuel avg. Hers was 13.8 mpg and she does not drive on the freeways. I drove and got it up to 18.8 mpg for the 25 mile trip to my daughters house. Just taking it easy on the freeway at 62 mph. Tacking 2000 rpm, no drafting, just with my foot. On the trip home i reset it and avg 25.2 mpg with my foot, about halfway home i put it on CC at 65 mph and used the CC controls to speed up and coast. Mpg went up to 26.9 mpg vs my foot. This really opened my eyes as i thought i was doing really well with my foot. I am now using CC on the Mazda on the freeway and use the CC controls to slow/speed up. I just did not know how much i would gain from it. Now i know. This van also has a big 4th gear 1,0,69. Most have 1,0,71. I will post up the results for the Mazda when i finish the 5 gallons.
If you live in the plains states, CC is the way to drive most efficiently. I recall that a Chevy Astro van (2000, V6) I used to own would only do 15-18mpg on the highway with my foot according to the display. When I went on a long trip to the middle of the country, I achieved the best mpg ever at 21.1 mpg. That was only possible in the flat states with the CC set at 70mph. (prior to knowing how to hypermile)
Where I live CC just isn't practical. Not to mention the VX doesn't have it anyway.
My route was flat, with a automatic trans i would just leave it in CC. Even if there were some rollers i would just use coast to get into the proper rpm range and reset it. On the way down the other side it would be in DFCO. I have not used the CC until lately so now i will practice with it in traffic.
I can get pretty close to the same with or without cruise in my fiancee's mazda. I use it to not worry about speeding (for mpg and legal reasons) but it is annoying since i can feel it alter the throttle position every 4-5 seconds and watch the scangauge mpg follow suit.
1991 Toyota Pickup 22R-E 2.4 I4/5 speed
1990 Toyota Cressida 7M-GE 3.0 I6/5-speed manual
mechanic, carpenter, stagehand, rigger, and know-it-all smartass
"You don't get to judge me for how I fix what you break"