Mileage better than expected

Just returned from a 2,500 mile trip in 1991 OCC. Average mileage was 26 mpg on regular gasoline. Best was 27.5 mpg while traveling at night with AC off. I'm sure gald I bought a wagon instead of a truck. Looks cooler, half the price, keeps stuff dry and gets good mileage too boot.

you must drive about 65 mph then was it ethonal free gas? When they started that I saw a 3MPG loss with 'nal mixed in.

Cruised at 75 mph, passed at 75-90. Pumps indicated up to 10% ethanol.

You probably have the tall gears, 2.73. Appears you had a good trip.

No insult intended but that seems high for an average speed that high and 10% ethanol fuel, especially with a TBI engine. Did you use the odometer and gas pump method? It sounds as if it may have had a gear or tire change the makes it think it went more miles than it did.

Speedometer not certified but gauged accurate to within 2% on the high side. Definitely tall gears as sweet spot is between 70 and 90 mph. MPG measurement done with odometer mileage divided by gallons to full tank.

I have no problem believing that kind of fuel economy, I've gotten 22 mpg out of my 87 Pontiac Safari with a very tired carbureted olds 307 and while my 94 RMW is LT1 equipped I have already gotten 26.4 mpg out of it mostly cruising around 75 to 80mph on trips between Stevens Point and Oneida Wisconsin, which is roughly a 1 and a half hour drive on the highway.

And no I don't take it easy on the throttle, that fuel economy was made with me getting up to speed on the on ramps and the exchanges, and flooring the throttle anytime I went to pass traffic

Walterf wrote:

Cruised at 75 mph, passed at 75-90.  Pumps indicated up to 10% ethanol.

sometimes you get lucky and you get non ethanol out of one of those pumps. It says up to, so they can put the old regular in when they want too. I've experienced mysterious jumps in fuel economy on trips where all of a sudden one tank gets be 2.5-3 more MPG.

Sprocket wrote:

Walterf wrote:

Cruised at 75 mph, passed at 75-90.  Pumps indicated up to 10% ethanol.

sometimes you get lucky and you get non ethanol out of one of those pumps.   It says up to, so they can put the old regular in when they want too.   I've experienced mysterious jumps in fuel economy on trips where all of a sudden one tank gets be 2.5-3 more MPG.

I have also, but it always seemed to balance out with the next tank or the previous tank. Single tank fillups, especially when hot, seem to be pretty erratic. I have found the vehicles with a trip computer or Scangauge in them to be much more consistent which kind of confirms a tank fill consistency issue, at least for me. When we were on a multitank trip I would not calculate mileage until the end and the whole thing, or if really long trip a split for part of it. Scangauge in RMW is really nice to have for mileage if it setup accurately.

My 1996 Caprice wagon with 2.93 gears consistently gets 22+/- mpg at 75 mph, 800 mile round-trip runs on I-90 (NY to NH or RI) on cruise control most of the way when it's not climbing the Berkshires, Green Mtns or White Mtns. Premium no-ethanol fuel, mildly tuned LT1. I've checked the odometer on 50 mile stretches of measured miles, and it's within 1% of dead-nuts. If I flog it, it drops to 17 mpg, which is still pretty good for a 2+ ton car from the 1990s.