: MPG versus MPH



danoh123
11-04-12, 09:20 PM
Was driving from north of Boston to Portsmouth, NH on I-95, a coastal flat road. When driving 70MPH my trip computer my gas mileage indicated avg. of 26 MPG. At 55MPH I got 29 avg MPG.

arw1510
11-04-12, 11:17 PM
amazing

Mamas.Pearl
11-05-12, 01:06 PM
Less wind resistance = better mpg.

danoh123
11-05-12, 02:05 PM
It was a perfect weather. Very little wind.

00 ss
11-05-12, 06:23 PM
To double your speed, you cube the horse power required, so slowing down requires less power in the same conditions. Using less power = using less fuel as long as all the engine managments systems are working properly. Were you surprised by this result?

danoh123
11-05-12, 08:01 PM
No, in engineering principal, but yes on degree of improvement. I had some doubt on Cadillac's MPG rating. I was testing the truthfulness or real life MPG rating of 2010 3.6 AWD

tinman
11-06-12, 09:09 AM
No, in engineering principal, but yes on degree of improvement. I had some doubt on Cadillac's MPG rating. I was testing the truthfulness or real life MPG rating of 2010 3.6 AWD

Better than the Kia and Hyundai...

Mamas.Pearl
11-06-12, 11:24 AM
It was a perfect weather. Very little wind.


..... what???


i was reffering to the speed. 70mph is 70mph of air/wind resistance..... 55 mph is 55 mph of air/wind resistance....

slow speed = less air/wind resistance.

reciprocity
11-06-12, 11:37 AM
Slowing down to 55 MPH definitely increases the fuel economy. It's really interesting, though: I've noticed if I go the speed limit (65), I get noticeably worse gas mileage than if I go faster (75-80 on some flat stretches of highway where we have a higher speed limit). It increases from about 24 MPG up to 29-30 MPG, calculated manually and with the computer. It's reproducible, so I don't think it has anything to do with tail winds or luck.

That being said, the best mileage I've gotten in the 2009 CTS is when I followed my parents in their '31 Model A, coasting along on back roads at a breakneck 35 MPH (about a 100 mile trip). I wish I could get the same *48 MPG* on a daily basis (although that was a really boring pace!).

00 ss
11-06-12, 12:23 PM
I can't stand to go slow for long periods of time. You must have ALOT more patients than me. I love the higher speed limits we have out west, but it does cost me a few more $$ in fuel costs. The majority of my commute is done at 75+ MPH.

tinman
11-06-12, 12:29 PM
I would take that trade off, too. More speed, Scotty!

danoh123
11-07-12, 09:33 AM
I can't stand to go slow for long periods of time. You must have ALOT more patients than me. I love the higher speed limits we have out west, but it does cost me a few more $$ in fuel costs. The majority of my commute is done at 75+ MPH.

I hear you. 55MPH was ONLY for a test short period of time ... My wife told me to speed up when I was doing 55 MPH :)

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I can't stand to go slow for long periods of time. You must have ALOT more patients than me. I love the higher speed limits we have out west, but it does cost me a few more $$ in fuel costs. The majority of my commute is done at 75+ MPH.

I hear you. 55MPH was ONLY for a test short period of time ... My wife told me to speed up when I was doing 55 MPH :)