Higher speed not as bad as I thought

[mrmad]

Originally Posted by Lug_Nut

Remaining in the right lane at (or just below) the posted max limit offers some advantages which I can't ignore.
1: Fewer speed changes than the speedup-slowdown-speedup 'slinky' effect of trying to maintain following distances in the lemming-line invariably in the center of the three lane.
The result is a steadier speed with the maximum very close to the average, versus the same average a lane over but higher maximums immediately followed by braking.
2: Usually (at least here in New England) less traffic in the far right.
On long rolling hills where one could see a mile or so ahead it is not uncommon to see 15 cars in the "fast" lane, 30 to 40 or so in the 'half fassed' lane, and but three or four in the 'slow' lane with me.
The result is more time to anticipate any of the fewer changes in speed.
3: An escape route on the immediate right. Not always, but usually. Some of the interstates in the Boston area permit driving in the breakdown/emergency lane during peak commuting hours when this advantage to the right lane is useless.
Anything going wrong in front of me in my lane can be easily avoided by a quick move towards, or even into, the empty lane to my right. The half fassed drivers not only are possibly hemmed in by traffic on each side, but their proximity to the vehicle in front of them limits sight line and time.
4: And finally the 'passivity' of selecting a slightly-less-than-the-average speed and sticking with it transfers the 'active' avoidance obligation to those approaching from behind. My "just under" the max limit mantra means I'm not doing to be rear ended since any closing rate would be but a few mph. I seldom gain distance on any of the few vehicles in the right lane, but when I do I have ample opportunity to pick up (or even slow) my pace to match the mediocre traffic to my left, select a suitable gap that may appear in that lemming line, slide into the queue, complete my pass, slide back out and resume my customary pace.

There are limitations to this technique, and each day may have different situations requiring different actions. When the posted is 65, but the slowest are going 75, there is no way in hell I'm going to drive just under 65. I'm not entirely stupid, I'll do 75.

I guess things are different in New England. I commute between Temecula and San Diego on I-15 each day. Each side has 4 lanes and even at 5:00 AM, it's amazing how much traffic there is. There are 3 large hills/small mountains on the trip such that you are either climbing, or coasting for most of the trip. The semis are stuck in the 2 slow lanes and enevitably, one truck will always seem to be going 25-30 climbing one of the hills. In a little CRX, you can't see more then the back of the trailor in front of you and not wanting to loose momentum, the other semis going 50-60 will make radical lane changes to get around the slow ones. Going fast enough to be in the third lane gets away from this.

[smay665949]

In my car there is no difference in mileage between 70 and 80 MPH (interstate driving outside urban areas). What kills me is when people are driving 5-10 MPH below the speed limit so I have to slow down and speed up all the time (I lose 2-4 MPG immediately when this happens). It is worse when individuals are driving slower than semis in the right lane requiring the semis to pass which causes cars to back up behind them. When this happens everyone is cumulatively wasting gas. The best things to do are drive the speed limit, use your cruise control and keep right unless you’re passing. If everyone follows these simple steps we can cumulatively use less gas.

[2TonJellyBean]

smay, my vehicle's mpg is dropping fast by 50 mph. So that'll me me, in the right lane, likely going somewhat under the speed limit, rolling off speed up hills and pulling the speed back up when descending. Sorry... my mileage at 70-80 mph would be a mortal sin.

[smay665949]

Thats cool that you get that kind of milage. Maybe you can help me understand your goals. Do you want to save yourself money on gas or do you want to save the environment, dependence on foreign oil etc. by using less gas/diesel (cumulative)?

Imagine a 2 lane interstate (1 way) and a 75 mph zone with someone driving in the right lane at 50mph. Big rigs that have to make a schedule are trying to run as close to the speed limit as possible. When they come on someone driving 50 they have to slow down to 50 mph and wait for a chance to pass. When they finally get a chance to pass they consume more additional fuel in 2 minutes than the 50 mph car will in an hour. Then add 3 cars that want to drive the posted speed limit who have to slow down for the truck. It’s a snowball effect that ends up wasting not saving gas/diesel (cumulative).

Understand that I am talking about driving away from congested areas with long stretches between stops. In congested areas this won’t work unless you’re on the autobahn in Germany.

[2TonJellyBean]

I get your point... but I don't totally agree and I do want to save my gas. I'm cheap and proud! ;-)

Nearly all cars are hugely less efficient at that speed (75 MPH)... many drivers know this and drive at better speeds. The maximum is just that. People should be free to drive at a speed up to the maximum but at least at the minimum posted and then do what;s best for them.

As for fuel losses it really depends on how much they are paying attention. If they have to hit the brakes they lose big time. If they decide to floor it, they lose again big time. Speed bleeds pretty easily at that speed, I'd say many cars would have a net gain - same rationale as pulse and glide.

I'd actually like to see speeds reduced near the crests of all hills to encourage more eco driving.

[trebuchet03]

Originally Posted by smay665949

Imagine a 2 lane interstate (1 way) and a 75 mph zone with someone driving in the right lane at 50mph. Big rigs that have to make a schedule are trying to run as close to the speed limit as possible.

On my cross country trips over the summer, a great deal of the long distance truckers were hanging around 55-65 on the flats (speed limit being 70-75). It's cheaper for them to go slower and save on fuel then get paid a little more for faster delivery - the gents I met got paid by the mile, and while there was a schedule to keep, they said they could go at slower speeds and keep it without any extra long hours.

Maybe it was just my route - but it makes complete sense to me

[smay665949]

I guess I don’t fit the profile of a typical Geo Metro driving gassaver.org member. I am an old performance nut I have had fast cars and trucks all of my life. In addition I have grown up around farms in the high country of Colorado where you need 4X4 trucks.

I own a 2001 Chevy impala with a 3.8 engine rated 28 MPH highway by the EPA. Since 2001 I have accumulated 205,000 miles with 2/3 of them over 65 mph. With the number of miles I know this car. I have never had a car that had so little rolling resistance as this Impala, on small grades with the cruise on I have to be careful not to have it coast more than 5-8 mph and end up with a ticket. If I drive long distances on the interstate with no other cars around it gets 31 MPG driving 65 to 85mph. On country roads (55 mph) I have gotten as high as 32 a couple times. I have never gotten below 25 in town or otherwise. A 79 Z28 I built in the 80s got 18 mpg at 55 to 100 if I used the cruise. I think the reason these cars don’t have much mileage variance in the higher speed range is that they have ample horsepower.


I recently switched my Impala’s engine to Amsoil. I typically got 27 mpg on my 102 mile round trip to work which includes some in town driving. If there is a lot of traffic I usually drop to 25 mpg. My wife burned the first tank of gas after I upgraded the oil and got 30 mpg, which is unusual because of her driving style (1. lead-foot 2. she probably didn’t fill the tank as high as I do). The next tank I got 27 mpg in traffic conditions where I normally got 25 mpg and continue to see 28 and have squeaked by with 29 on a couple tanks (without traffic). I have not taken a long trip to see if I increased mileage over 31. In addition I get 26 mpg in the winter instead of 27.
I have also converted my wife’s VW New Beetle, that I has never gotten over 26 mpg, to Amsoil last week. So far I have noticed power difference in her car but have not checked the mileage.

I also have a 95 F250 Ford 4X4 with a 7.3 Powerstroke diesel that I get 19 mpg on the interstate as long as you keep it under 75. I have driven back roads (55) and have yet to get over 19. Driving 78 mph starts the drastic loss of economy with any of these diesel trucks. My goal is to get this truck to 24 MPG with Amsoil, aftermarket exhaust, performance module and boost/pyrometer gauges. (One cool thing about increasing power on diesel trucks is that you increase mileage if you don’t go overboard and if you watch your pyro. gauge you can know when to shift by the temp of your exhaust.) I am tracking mileage on every tank so I know how much each mod increases mileage and performance. Some of these mods will be useful for any car and I will post the results as I gather data.

http://www.lubedealer.com/T&SMay/