Highway mileage

Unfortunately going there and back from a place aren't really comparable. One may be slightly uphill while the other one is slightly downhill. Interesting to see that even at 74MPH that you still got 42 MPG, but I don't think those are very comparable.

 

I do 90 miles a day at 70+ mph for most of the trip. Lifetime average is over 50.3 mpgs, in 38,000 miles over the last year and a half +. Its almost impossible to drive the same exact road at a given speed for comparison. I guess you might use the Scan gage to compare average speed over the same trip every day, and get a ball park comparison of speed vs. mpg. One trip won't provide much data. Just drive the car. Don't think too much about it. The Prius will do better than any other car you've probably owned, at least for me.

 

<div class='quotetop'>QUOTE(aeronaut @ Jul 26 2007, 10:06 PM) [snapback]485883[/snapback]</div>

The AC will not impact your mpg on the highway significantly since it is operated by the battery which is almost always fed when in CC a high speeds.

What tire pressure are you running?

 

lights on? that matters?

 

Running the A/C reduces my highway mileage by a reliable 7-8%. (That's better than my old Accord that was hit by at least 15%...chalk it up to the variable speed compressor working its icy magic.) It may not drain the battery like it does in city conditions (ouch) but it does require a fair amount of energy to move all that heat up-hill.

 

<div class='quotetop'>QUOTE(brick @ Jul 27 2007, 08:33 PM) [snapback]486471[/snapback]</div>

That sounds similar to what I've seen. In particular, I've found that setting the auto climate control in the mid 70F range, with the car in full sun at noon when the outside temp is 85F to 95F, the A/C uses around 0.15 to 0.20 gallons per hour. If the car moves 1 mile in that hour, Ouch. Big hit to your MPG. If you are traveling at hwy speeds for that hour an additional 0.15 added on to the 1.5 gal or so that you are burning anyhow is only a hit of 10% or so. Less if the temp outside is cooler, it is overcast at all, or you bump up the interior temp a bit.

 

<div class='quotetop'>QUOTE(aeronaut @ Jul 26 2007, 10:06 PM) [snapback]485883[/snapback]</div>

as far as break in, I drive mostly (70 %) in urban highway situations (heavy traffic 55-60 mph) and somewhere around 7500 miles I hit a break in point where no matter what, my mpg will stay above 55 regardless of A/C, and traffic conditions. My original goal before ownership was 50 mpg, then i bumped it to 55 (now approx. my lifetime avg). Now after about 20 tanks, I have frequently flirted with 60 mpg and just barely busted it twice and now my goal is to try to bust 60 more regularly and start flirting with 64 (double my last cars 32mpg) To help today i just boosted my tires from 42f / 40r up to 45f / 43r.

 

<div class='quotetop'>QUOTE(morpheusx @ Jul 28 2007, 09:39 PM) [snapback]486880[/snapback]</div>

OH NO! You went over the tire manufacturer's max sidewall recomendation? I predict doom, destruction, and disruption of the space-time continuum.

 

<div class='quotetop'>QUOTE(diamondlarry @ Jul 29 2007, 12:53 PM) [snapback]487096[/snapback]</div>

LOL

 

On the last day's leg of my return trip from Hybridfest [over a week
later, ahem] I finally caved and ran the a/c for most of the mid-
day's run just to keep the oppressive humidity down. Parked it at
something like 76F with low to medium fan. The compressor ran pretty
hard at first but then settled down. I kept it in recirc mode,
too, trying to avoid bringing in more wet air that the system would
have to pull the latent heat out of. Drove as I usually do, keeping
RPM between 1700 and 2400 with occasional hill-climbing excursions
toward 3000, and was showing 64.3 average when I finally tanked up
in Waterbury CT [eww]. As the sun was well over the yardarm by then,
I ran the rest of the way home without a/c and the "diagonal window
slits" trick, and still held north of 62 mpg.
.
The tanks for my whole trip seem to average 61.7.
.
_H*

 

I may be able to help -- I did a MPG vs MPH test early on with my '05, see my signature. I just re-uploaded the attachments, as they seem to have expired...

As far as break-in, I now have 19,000 miles on the car, and "maybe" I am just now seeing a change. Hard to say, but temperature sure makes more of a difference!