I drive 36 miles round trip to and from work on Interstate 5.I have been driving 60MPH and to be honest I'm getting tired of it. I sure would like to drive 70 - 75 like the rest of the worlddoes it really make a huge difference driving 10-15 MPH faster? What do you guys think the difference would be.
MPG difference?

 

Yes it does, at 65 my computer shows around 17-19 depending on hills. At 75 it shows more like 13-15, and worse from there. I realize these things aren't exceedingly accurate for that purpose, but it gives you a good comparison. Where I live though, if you do 65 (which IS the speed limit on the highway) you get in everyone's way.

 

same here, so i do like 75-80....i know my MPG could be higher if i drove less fast, but i dont want to the fukcing retard holding everybody up and everyone has to go around that person. and plus i feel like im crawling doing 65 on the highway....**** i do that on some roads

 

hell with the 35's on i do around 80 at about 2K rpm.. i never tryed to figure out my best gas mileage speed.... i know it wasnt 115[8D]

 

Except for the construction zones, I usually run around eighty. In one brief test last November, my O/H console showed 17.8 mpg. Flat ground and cold air. Going on a road trip tomorrow. Planning to do some more careful computations using different grades of gas. The trip won't be long enough to try a lot of different speeds. Plus, we'll be on I-75. If you don't run eighty there, you get run over!

 

Well you could look at the big picture and see that if you drove just 15 mph faster, you would shave 15 minutes or so off you total drive time each day. Take into account that the average american has 252 work days, you would add an additional 2.5 days of free time a year.

Now driving at that extra speed, you would roughly burn 1 extra gallon a week in your drive time with the loss of mileage. So in 1 year times, you would spend an extra estimated $190.00 in gas over the course of the year assuming you have 2 weeks vacation and the price of gas stays roughly the same. (BTW, I just took an average price of $3.80 / gal. for the gas).

So now that you have the BIG picture, is 2.5 days worth $190 to you?

1 thing not counted in is if those speeds are actually speeding, if you get caught speeding and get a ticket.

 

I live in Denver and I have to tell you, on the I-25 stretch between Castle Rock and say north Denver, you dont see many people speeding a heck of a lot anymore (there was actually a study done here recently), that fuel mileage has a bigger effect on people speeding now days that tickets. So what used to be a 70+mph or get out of the highway stretch is now easy 60-65 miles per hour.

Honestly a tank lasting me 2 more days of comuting by doing 60 makes a difference to me. Much like L & R noted above. What is it worth to you? Bottom line, yes.. anything over 60MPH in our aerodinamic bricks makes a huge difference in MPG.

 

it does make a difference. well, if you have an 06 or newer, you have mds which only work when you are going under 70. soooo... i drive under 70 for that. i get better mpg doing so.

 

Ok so heres what I got, I became curious after reading an article about this very topic. I have an 06 QC 5.7 and did some of my own generic testing driving the exact same road, same lane and cruise control set.

60 mph 21.4 mpg
65 mph 17.8 mpg
75 mph 15.1 mpg

Just a quick glance tells me that if I was to do a serious road trip I would be taking my time seeing that with a 34g tank and current gas price of $3.29 thats $111.86 to fill her up. So we are talking in theroy that @ 21.4 mpg that road trip will yield me 727.6, @ 65 mph it would be 605.2, and @ 75 mph 510. Now are those numbers real probably not but thats how the numbers crunch out. Now if your time is far more precious than your pocket book, or if you don't want to be that a$$hole holding everyone up then ya I would go for the 75 mph cuz in these tanks anything slower feels like the snails will be passing you.

Now there are other factors that would come into consideration with these numbers in theroy, wind, temp and obviously other vechicles on the road gettin in the way.

 

That is not true I have had my mds kick on at 85 not just ones either, about every time I drive that fast I get it to kick in.