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-   -   Your speed on the Highway (https://electricvehicleforums.com/forums/fuel-economy-emissions-22/your-speed-highway-15701/)

spinner 11-17-2007 06:26 AM

Re: Your speed on the Highway
 
I don't get it either. The advantage of CC is to maintain a steady speed and hopefully a steady engine speed, both of which contribute to better fuel economy. I don't mind if the engine has to speed up to take a hill because I get something back on the other side. If I try to maintain speed myself, there will be lots of variance while I try to adjust speed. That does no good for fuel economy and it can be seen as a lack of courtesy to other drivers, particularly for transport trucks that follow behind. We know that freeway speeds are not the best for fuel economy, that the faster you go and the steeper the grade the more horespower will be required to keep up.

This isn't meant as a personal challenge. My opinion of driving on freeways is to leave the fuel economy excercises to secondary highways (reduced speed limits). Our vehicles are already working hard to find efficiencies in our drives. Second-guessing them all the time can be counter-productive and unsafe.

CA Girl 11-17-2007 01:03 PM

Re: Your speed on the Highway
 
Hmm... if the roads aren't clogged then I am going somewhere between 60-75 depending on whether I am in a hurry or if I just spotted the CHP waiting for someone to zoom by them!

I don't like the cruise control for my driving here in the SF Bay Area because of the rolling hills freeway driving that I do mostly. Tho, I know that on a longer trip on say I5's flatter spots, I would use the CC.

Have also noticed that my mileage isn't necessarily better at 60 or 65. What I have noticed is that if I can keep the car moving at a steady 68-72 on the freeways here, my mileage does well.

How come no one has mentioned the fun of passing people on the downhill stretches that glared at you on the uphill stretch? It brings a :) to my face when I pass those hummers or beamers coasting downhill doing 70mph and my mpg is reading 60mpg!!! :shade:

kenny 11-17-2007 03:01 PM

Re: Your speed on the Highway
 

Originally Posted by spinner (Post 150286)
I don't get it either. The advantage of CC is to maintain a steady speed and hopefully a steady engine speed, both of which contribute to better fuel economy. I don't mind if the engine has to speed up to take a hill because I get something back on the other side. If I try to maintain speed myself, there will be lots of variance while I try to adjust speed. That does no good for fuel economy and it can be seen as a lack of courtesy to other drivers, particularly for transport trucks that follow behind. We know that freeway speeds are not the best for fuel economy, that the faster you go and the steeper the grade the more horespower will be required to keep up.

That kind of depends on the hill and the speed.

If it is a steep hill and high speed CC will try to maintain that speed, and inhale as much gas as nessesary to make that happen.
If it was a hill for which you could tolerate a slower speed at the top then you just wasted some gas using CC compared to taking over and letting the speed drop at the top.

I am a heavy CC user but there are two high bridges I go over.
Most cars fly over the top at 65 miles per hour but all the huge big rig trucks are going only about 30 miles per hour at the top.
So I stay in the right lane and creep over the top with the trucks.

Then on the way down I try to adjust my foot on the gas so I see no charge or accelerate bars.
This means I am flying about 68 miles per hour at the bottom.
My MPG always returns to what it was before the bridge.

If I left it on CC I'm sure I'd lose some of my "score".

Irunnoft 11-17-2007 08:35 PM

Re: Your speed on the Highway
 

Originally Posted by bwilson4web (Post 150221)
Hi Jim,

Welcome to the CLUB!


You might head over to the Prius forum and read up the FAQ. This will give you some tips that will let you come closer to 65 miles per hour and still get excellent mileage.

GOOD LUCK!
Bob Wilson



Hi Bob!

Thanks for the welcome and the info!:) I'll be going over to the FAQ to check out those driving tips. I've skimmed the website and not really had the time to devote to pouring over the pages yet, but I've come across terms like "pulse and glide" that have my interest piqued! I can't wait to learn all I can about this new car. It's really funny, but this little car has totally changed the way I approach driving. I never thought it would've effected to such an extent. Honestly, it's been a long time since I was this excited about an automobile. I know it makes me a geek....but I love my Prius!:shade:

pennylane 11-19-2007 07:17 PM

Re: Your speed on the Highway
 
yup, cruise control's my friend :D

__________________
on this month's blogroll: Chevrolet truck blog

DoPeY5007 11-19-2007 11:06 PM

Re: Your speed on the Highway
 
Around 70, cause if we don't we get ran off the road

snax 11-20-2007 07:01 PM

Re: Your speed on the Highway
 

Originally Posted by spartybrutus (Post 149682)
Basjoos - LOL, You and Kenny are at the extremes... him slow with CC and you fast w/o CC and both knocking out big FE numbers month after month...

:star:

And Basjoos does it without hybrid tech. Imagine what hybrid owners could do if manufacturers got serious about aerodynamics and offered manual transmissions with all hybrids.

Our 5-speed Mazda5 does not suffer on economy by maintaining speed up hills. It actually gets 2-3 mpg better on hilly terrain vs. the flats by simply coasting the descents with the engine idling.

We pretty much just keep pace with traffic on two-lane highways and stick with the speed limit on the multi-lane ones. (If there's traffic to pace, it's more efficient to go a little faster if necessary anyway.)

TheSpoils 11-25-2007 11:11 AM

Re: Your speed on the Highway
 
When I get to the top of the hill, (not on cc) i have usually slowed down to the speed of the trucks around me, (around 30-40MPH) i then allow the ev to kick in and put the car in neutral. Within 10 seconds I will be traveling 60-80 MPH on ev mode downhill, without using gas or elec power. My MPG gauge tops off at 99.9 mpg and thats what im getting.
I cannot do that with CC on.

Hot_Georgia_2004 11-26-2007 06:43 AM

Re: Your speed on the Highway
 
Regarding other drivers, I believe every region is different.
I hear about terrifying instances of flashing lights, horns and rudeness from some people in other places while traveling the Right lane and exceeding the speed limit.

The only time I've experinced this in 4 years is the two days I had a "I get 65MPG...YOU?" bumper sticker. I removed the sticker and immediately went back to normal.

Around here,
80% of the people driving on a 70MPH limit two lane divided freeway are driving 70-78MPH in the Left lane, while others drive 58-70 in the Right.
I generally drive the 58-65MPH, depending if I'm going up hill or down hill.
Sometimes I'm lucky enough to remain safely behind a slow moving truck down to the low 50's.

As I'm driving ~60 in the Right lane, almost everyone passes by on the Left lane. People usually follow me a hundred feet behind and either politely go around or just stay behind for miles- sometimes 10 miles or more. Occasionally I'll pass a slower moving vehicle(s) but not very often.

If the speed limit is 55 or 65 then I'm on a multiple, 5-7 lane freeway and again, all the way to the Right. My speed is 53-65.

In a 45 speed limit I'll be going 35-50 if there's nobody behind, and 42-50 if someone is behind.

Since I haven't experienced any flashing lights, horns, gestures or severe rudeness (like cuting off etc) I believe I'm driving courtiously.

I had the opportunity to extremely hypermile my car for the 1st 3 years. I drove a perfect commute, and was able to safely do all kinds of techniques at 3AM on abandoned rural highways.
My all time record is 1004 miles for 74.9MPG on a single tank.

About a year ago my commute radically changed and had to make some driving adjustments. Today I rarely key-off and roll, I roll less stop signs and don't alter my route to favor MPG. I don't draft or P&G.
If I see one of those "Packs" or "Groups" of fast drivers approaching, I'll usually increase my speed somewhat, for a closer match until they pass.

As a result I'm no longer averaging +65MPG tanks. Today I'm averaging 55-61MPG tanks in the mild GA weather. That's OK with me.

My work is about 50 miles from home, and I spend 18-21 hours a week in rush hour traffic. That's 3 to 4 hours a day. Sometimes I'll leave the house at around 5:30AM and beat the traffic. I get to work in an hour- but arrive 4 hrs early so I don't do that very much.

Cruise control:
CC is good to use if:
1. You are not used to driving for economy
2. Able to accept the boredom of it
3. Drive on a road where you can keep it engaged (lack of traffic)
4. Commute on flat roads

CC is not the best if:
1. Tend to get bored of it, disengage and drive faster/harder than you normally would
2. Not the best for maximum economy.

CC will not compensate for varying traffic. It can not view the distance to the car ahead, certainly not several cars or even miles ahead and can't make the adjustments neccessary for maximum economy in a changing environment.
CC will maintain speed up hills, thoughtlessly burning off excessive fuel all the way up. Kenny (and others) have mentioned this.

A more economical way to climb hills are to allow your speed to drop to a minimum level as you reach the top. No, you can't always do this for traffic but you'd be suprised how many times you can, and still be a courtious driver.

I also find the CC uses the Assist more often and more agressively than if kept off. Less used batteries generally last longer which gives me more peace of mind.

-Steve

basjoos 11-27-2007 02:21 PM

Re: Your speed on the Highway
 

Originally Posted by CA Girl (Post 150318)
It brings a :) to my face when I pass those hummers or beamers coasting downhill doing 70mph and my mpg is reading 60mpg!!! :shade:

It brings even more of a smile as you are accellerating steadily with the engine off, propelled solely by gravity, silently passing through 70mph and getting infinity mpg. But as you pass them you can hear their engine running since they are having to use it to keep their speed up on the downhill because their vehicle has so much aerodynamic drag that gravity alone won't do the job.


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