21746 messages,
Last post on May 21, 2013 at 7:38 PM
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Car Safety
Sep 11, 2012 (10:54 am)
...proved you can go over 100mph in a Prius, FWIW.
#19708 of 21746 Re: Go fast in Texas! [bobw3]
by xwesx
Sep 11, 2012 (11:41 am)
So then I guess the crux of it is... what is more important to you: Time being bored or cost of fuel used during that time?
#19709 of 21746 Re: Go fast in Texas! [bobw3]
by fintail
Sep 11, 2012 (11:46 am)
But how much money saved vs time? It is again all a personal decision. If I can get 30mpg at 70mph but 32mpg at 50mph, I am going to choose the faster speed. What is "illogical" is subjective.
I wish I lived in a place where 60 was the right lane. You can be in the left lane a lot at that speed, especially on 405, where the right lane often moves at 45-50. You'd love it here! Think of all the money saved
Thanks for the good wishes, and you can enjoy your turtle crawl - just stay in the lane where you belong, and maybe stick to scenic state highways as you have nowhere to go and all day to get there anyway
#19710 of 21746 Re: Go fast in Texas! [fintail]
by ateixeira
Sep 11, 2012 (11:55 am)
If I can get 30mpg at 70mph but 32mpg at 50mph
With DC traffic it's option C, 26mpg at close to 0mph.
#19711 of 21746 Re: Go fast in Texas! [fintail]
by andre1969
Sep 11, 2012 (12:03 pm)
But how much money saved vs time? It is again all a personal decision. If I can get 30mpg at 70mph but 32mpg at 50mph, I am going to choose the faster speed. What is "illogical" is subjective.
Back in 2008, when gas prices were getting expensive, I remember driving my 2000 Intrepid up to PA to go to the Ford Show in Carlisle on one brutally hot June day. Just out of curiosity, I tried hypermiling it. No a/c (this was early in the morning, before it got hot). Tried to keep the speed around 55-60, which was hard to do, and I did get up to 65-70 once or twice. MPG on that run was 32.1 mpg, which I think is the best I ever got out of that car.
A few months later in October, I went up again, for the Fall Carlisle swap meet. This time I averaged more like 65-70 mph, with perhaps an occasional jaunt to 75 or 80. Flow of traffic, more or less. Fuel economy on that run was 30.82
The following week I went back up for the show in Hershey, PA. This time, I was running around 70-75 for the most part, and again getting up to 80 on occasion. This time around, 30.01.
So really, not a huge difference IMO. And going at those slow speeds like I did the first time around can actually be dangerous, when there's too much speed disparity between cars. Now, that first time I did it, everybody seemed to be going a bit slower, no doubt in reaction to gasoline that was approaching $4.00 per gallon for the first time. So, it wasn't as bad. But, now that people have gotten used to high gas prices and are driving faster, I'd be afraid to go that slow on my PA run.
Making that trip up for Hershey can be pretty adventurous too, as sometimes you'll get some old fossil who takes their Model-A or something similarly slow and putts along at 35-40 mph.
#19712 of 21746 Re: Go fast in Texas! [andre1969]
by bobw3
Sep 11, 2012 (12:31 pm)
I agree...if you're really only getting 2mpg more by going 55-60 vs 75mph, then I wouldn't worry about the MPG savings either. But from what I've read and experienced, most people will see a lot better MPG improvement that what you're seeing, but it does depend on the specific vehicle. That's the way statistics and averages work out.
#19713 of 21746 Re: Go fast in Texas! [xwesx]
by busiris
Sep 11, 2012 (12:33 pm)
I'm not sure where your argument is trying to go.... Nobody stated the contrary. The counterpoints were simply that fuel economy doesn't necessarily vary as dramatically at different speeds, depending on the vehicle, as what that website presented, and saving fuel is not necessarily the most important factor for the driver.
Overall, well stated.
I would only add that, in many modern models. say a BMW, Audi, Chrysler 300 or Lexus (there are many others) the fuel savings one might see are so small as to not be of any major importance to them.
Im not advocating speeding, but at least to me, going 60 on a 70 MPH Interstate highway just to get 32mpg .vs. 30.5 mpg, over the length of a 5-6 hour trip seems like poor justification for running 60. Now, if the mpg ratings were 32 .vs. 16, its a different story altogether... but in reality, it isn't.
#19714 of 21746 Re: Go fast in Texas! [busiris]
by ateixeira
Sep 11, 2012 (1:24 pm)
I bet the gearing would have a major effect.
Some autos have 8 ratios now, so they can lower RPMs waaaay down at high speeds. CVTs also have a very wide range of gearing.
I heard the new Outback can go nearly 80mph at just 2000 or so rpm. That sure helps.
Of course rolling resistance decreases linearly, while aero resistance increases in a non-linear manner, so you still give up something.
#19715 of 21746 Re: Go fast in Texas! [ateixeira]
by ruking1
Sep 11, 2012 (2:13 pm)
Anymore between normal operating parameters, the car is designed to get as good mpg figures as possible. In a normal commute (09 TDI Jetta) with an average speed of 18 to 36 mpg (1.5 to .45 min) over 27 miles per trip we get between 39- 42 mpg. When cruising ( 90 mph or slightly less) without thought or fanfare (actually close to a no brainer) post 40-42 mpg. This is on a EPA rated vehicle of 29 C 40 H.
Now, we also get similar mpg results with a 03 Jetta TDI only (slightly) better range of 48-52 in both scenarios. A steady 90 mph will post 50 mpg. Any number of times I have run 584 miles in 6.25 hours for a 12.1 gal fuel stop and posted 48.26 mpg.
So yes the theory is great and all. However the real world gets ,.... in the way !?
#19716 of 21746 Re: Go fast in Texas! [andre1969]
by fintail
Sep 11, 2012 (1:38 pm)
Interesting, your mpg results aren't too far off what I posted - different cars, but the decrease in mpg with significant speed increase was not remarkable in either car.
In a couple days, I will take a small road trip in the E55 - I will average around 65mph, which will return around 25mpg - not unacceptable for a relatively old school gas swilling tuned V8. I'll keep proper lane positioning and wager I won't cut anyone off or obstruct anyone, either. I am usually considerate, until horn honking time comes around