interesting MPG numbers from this weekend

[lostatlantis]

So I had to drive about 180 miles each way this weekend. I'd say 90%+ highway.

First leg: hit some rush hour traffic on the way out, but no complete crawl, I'd say 40mph to 60 mph during the rush; later on, followed traffic flow and had some stretches of 85mph, with some short bursts of 90mph. A/C on about 60 to 70% of the trip

result? 194.2 mi on 6.711 gallons, 87 octane = 28.94mpg!

Return trip: got the idea that *maybe* driving 80+ mph HELPS with gas mileage... :) so started trip holding steady at 82 to 85mph. There were some short stretches of 90mph. Overall, more time going over 80mph this time around. A/C used maybe 5% of time (left about 7:30 pm)

182.4 mi on 6.7 gallons, 87 octane = 27.22 mpg.

Weird eh?

[98 3.8]

Re: interesting MPG numbers from this weekend

Makes sense. I've heard that for most cars, their most gas-efficient speed is ~45mph.

[Bonemaro]

Re: interesting MPG numbers from this weekend

Mythbusters did a show where they got better gas mileage with the windows up and air running that with windows down and no air. They assume it has to do with the extra drag produced by the air entering into the passenger compartment.

[josh98bird]

Re: interesting MPG numbers from this weekend

I figured the difference would be a little more than that... so it looks like pretty much either way of driving produces similar mpg. I have noticed that I do get better gas mileage with the windows up or cracked instead of down.

[lostatlantis]

Re: interesting MPG numbers from this weekend

Mythbusters did a show where they got better gas mileage with the windows up and air running that with windows down and no air. They assume it has to do with the extra drag produced by the air entering into the passenger compartment.

That makes sense, if you think about it the back window would act like a big drag chute.

However, I remember watching a Mythbuster episode on this topic and they said it's better to OPEN up your window than A/C, because the air moves over the stagnant air smoothly just like over the back of a empty truck bed with the tailgate up.

I figured the difference would be a little more than that... so it looks like pretty much either way of driving produces similar mpg. I have noticed that I do get better gas mileage with the windows up or cracked instead of down.

My windows were all up once on highway. When A/C wasn't on, vent was. Midway through the return trip, I did have to turn the light on - maybe just a little more drag from the pop-up headlights.

I'd say the rush hour traffic portion of the departure was about 1/3 of the entire trip. So the real major potential difference here is driving speed, followed by A/C usage.

[Kronic Budz]

Re: interesting MPG numbers from this weekend

well your car gets good gas mileage!!! I hate you.

[lostatlantis]

Re: interesting MPG numbers from this weekend

By the way, it wasn't an empty car either. I was hauling a desktop tower + 17" CRT monitor, guitar, some electronic parts & couple books, rolls of posters.

I wonder what the milage would be if I drive at 55mph all the way through. Oh well, the world may never know :)

[Kronic Budz]

Re: interesting MPG numbers from this weekend

By the way, it wasn't an empty car either. I was hauling a desktop tower + 17" CRT monitor, guitar, some electronic parts & couple books, rolls of posters.

I wonder what the milage would be if I drive at 55mph all the way through. Oh well, the world may never know :)

whos knows, but would it really be worth it to drive 55 mph, thats to damn slow to drive in a fbody on the freeway, fastlane baby.

[lostatlantis]

Re: interesting MPG numbers from this weekend

well your car gets good gas mileage!!! I hate you.

haha well I range anywhere from 18 to 22 around town. Every once in a while I'll dip into the 16s. Feel better now?

[lostatlantis]

Re: interesting MPG numbers from this weekend

whos knows, but would it really be worth it to drive 55 mph, thats to damn slow to drive in a fbody on the freeway, fastlane baby.

Exactly, as in "the world may never know" :)

[josh98bird]

Re: interesting MPG numbers from this weekend

Last I checked with only me in the 3.8L M5 firebird with only mods whisper lid, free ram air mod, silencer replaced, and flowmaster

31.556 mpg from a 3 hour trip highway 99% and ran about 80-85

Its nice not having to shift into 5th gear until 70mph

[ReD715]

Re: interesting MPG numbers from this weekend

Gearing does play a little part in MPG. You guys might want to include that too;)

[98 3.8]

Re: interesting MPG numbers from this weekend

I just got 25.8 MPG with a full bolton car and 3.73s...and that tank included 13 1/4 mile passes. :p

[RadRacer]

Re: interesting MPG numbers from this weekend

Just pulled 27.8MPG with a full bolt-on and 3.73's. Includes 2 1/2 mile drags, and my leadfoot :P. If I babied this thing, and went on a total highway trip, I'm sure I could reach 35+ MPG :D.

As for the windows vs AC topic. Generally, windows down is better during city driving. At about 45MPH (IIRC), the drag created by the open windows is equal to the engine drag caused by running the A/C. As you go faster, the drag from the windows is just going to increase, where as the A/C drag won't. So, if you're driving in the city, windows down is gonna give better mileage, however, once you reach the interstate, roll em up and crank up the A/C and enjoy being cooler, and saving money :D

[josh98bird]

Re: interesting MPG numbers from this weekend

once you reach the interstate, roll em up and crank up the A/C and enjoy being cooler, and saving money :D

my A/C doesn't work :(