miles per gallon has no relationship with time.
I would imagine that if the journey took more time, then that means that the engine is on longer, which means that more fuel is being burned. Unless of course the engine was turned off regularly, which as pointed out above, is not a good thing and probably causes equivalent damage to the environment either way.
A little knowledge is truly a dangerous thing.
Not a LOT less but less.
Using MPG can be misleading. If you're sitting at a stop light, both a hybrid and a regular car are getting zero miles per gallon, but the hybrid shuts its engine off, so it's obviously using a lot less gas.
It makes more sense to measure in gallons per mile (or gallons per 100 miles to make it an easily understood number). It makes it easier to judge the relative difference in fuel economy between different cars. For example, if you don't do the math, it seems like the difference between 20 mpg and 30 mpg was the same as between 30 mpg and 40 mpg. But it's more clear if you look at 5.00 vs. 3.33 vs. 2.50 gallons per 100 miles.
But as others have pointed out, MPG is not a constant anyway. Stop and go traffic completely wrecks it (unless you're driving a hybrid), as does aggressive and high-speed driving. You can save gas from slowing down on the highway; the optimal MPG for most cars is surprisingly low; something like 40 mph.
A Prius actually gets a little better MPG in the city because of the lower average speed. It makes up for the stop and go with regenerative braking and shutting the engine off at stops.
When people zip by me I say "Way to save 5 seconds *******!" and have my son give them the finger out the rear window as they pass.
Drop off your mom at the nearest bus stop.Show Image(http://meanwhilepics.com/images/meanwhile/Meanwhile_In_Japan.jpg)
miles per gallon has no relationship with time.
What is the most demanding is acceleration. A slow steady acceleration and a constant low speed (according to the chart above, 40mph is best) will give you the best mileage.
Back to your case, for the same distance, constant stop and go will take at least 30% more gas than if you do it strait at a constant and relatively low speed. So it means that a highway path less than 30% longer will be more fuel efficient.
Hmm, I have read that best for fuel consumption is quick acceleration... Who knows...
That must come from a petroleum company propaganda.
When I floor my car the computer shows up to 50l/100km
Under normal condition it is more like 10l/100km
Do you remember F=MA?
The Force is directly proportional to the Acceleration.
The consumption is tied to the Force.
You're pulling my leg right? Was I candid enough to respond to your statement?
I guess yes :redface:
I zoom by them Thinking "way to save a quarter, skippy!"
.
Actually his wiki has pulled 700 legs. (http://geekhack.org/showwiki.php?title=Mechanical+Keyboards+Sorted+By+Switch)
But it isn't proportional to either time or distance. So you use same amount of energy to accerelate to same speed:
E=0.5mv^2 so the energy needed is same.
Fast and steady is better than slow and steady. Faster you get in gear the better...
Alas, I have found that if you want something done right in America you end up having to do most of it yourself.
Actually this would only be true to the point where the fuel still continues to feed the acceleration and the excess isn't going unused. Its possible to flood the engine with too much fuel, so when the rate of fuel being fed into it exceeds the rate at which it can be burned efficiently, that is wasting fuel by accelerating too fast.
Basically both of you are right on this, I think.
Back to your case, for the same distance, constant stop and go will take at least 30% more gas than if you do it strait at a constant and relatively low speed. So it means that a highway path less than 30% longer will be more fuel efficient.
That is very useful info. Where did you get that 30% figure? Is there an authority I can point at somewhere that has that posted (preferably next to a seal from the government or a logo from some other recognized agency she will respect (like Consumer Reports)?
http://www.fueleconomy.gov/feg/findacar.htm
How's your mom with Physics?
Note V (velocity) is CUBED!Show Image(http://us1.webpublications.com.au/static/images/articles/i1086/108648_10lo.jpg)
Drag coefficients, area and fluid density
^ Only a handful of formulas are clear out of context. This is a measure of power needed to overcome turbulent air resistance, it seems? [EDIT: Yup. U guys r 2 fast.]Show Image(http://us1.webpublications.com.au/static/images/articles/i1086/108648_10lo.jpg)
it does not include any kind of friction losses in the engine, transmission and wheels, nor any braking losses (which turn motion energy into heat after all). Some of those are hard to model with a simple formula as they are not directly dependent on speed, hence simulation and the resulting mileage vs. speed graphs. It is true that with increasing speed, air resistance starts dominating at some point.
In real world vehicles the change in fuel economy is less than the values quoted above due to complicating factors.