I just purchased a 2003 Honda Accord LX Sedan Automatic and moved to
Loaded down with all of my personal belongings, I got 32mpg during the
770 mile drive from Dallas. This was fine with me.
During the first few weeks that I was here, my driving was evenly split
between city, small highway (55mph) and mountain driving. I averaged
Determined to do better, I committed to keep the TAC under 3,000 for
the entire volume of gas in the newly-filled tank. I just filled it up
last night and did the calculation. 22mpg.
My eyes are crossing...
Almost all of my driving for this past tank has been city driving. I
have not been an A/C fiend, and I shift into Neutral and coast downhill
rather than let the engine do it. I take my time getting places and I
don't jackrabbit starts or stops.
What am I doing wrong? Or does Colorado just suck? Is my expectation
of 25mpg city driving unreasonable?
Yes it is, especially considering your altitude and mountainous terrain.
EPA estimates on the V-6 Accord are 21 city, 30 highway. In your
driving conditions, anything over the EPA city number is a good result
for city driving.
The altitude should not affect mileage. (Empirical evidence of this is my 91
Civic: Got 40 mpg at sea level for several months. Still getting 40 mpg at a
mile high altitude, late spring through fall.)
Driving in mountainous terrain may be the problem.
The car is two years old, though. It is about due for a tuneup. Have you had
one done recently? Check your owner's manual. It may specify new
at a minimum.
See, among others,
The lower octane gas in the Rocky Mountain states is appropriate for the
I doubt the lower octane affects fuel mileage.
Much of the speed reduction when going downhill is achieved by taking
your foot off the gas and letting the engine do the "brake" work. By
putting the transmisison in neutral, you have to rely entirely on
your braking system, risking rapid overheating of the brakes.
Overheated brakes work very poorly, leaving you open to destruction.
Larry J. - Remove spamtrap in ALLCAPS to e-mail
The United States is the greatest country in the world..!
apart from the very obvious danger of what you describe, coasting in
neutral also /raises/ gas consumption on an injected car. if the ecu
sees no throttle above a certain rev, it assumes coasting mode and shuts
off gas delivery entirely. it won't do that if it's idling because the
revs aren't high enough to register as a coast.
coasting in neutral could arguably save gas on a carburetted engine so
that's probably where this bad practice arose, but for injected engines,
absolutely leave it in gear all the time.
Great post. I just wanted to add that it's a bad habit to get into. I
doubt that it saves any gasoline. In addition, it adds more "wear" to the
transmission. In other words, your transmission will wear out quicker if
you shift into neutral every time you go downhill.
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On Fri, 19 Aug 2005 10:34:46 -0700, email@example.com (Jason) wrote:
We've just had a past that states it saves on carb cars, but not,
generally, fuel injected ones, which you obviously didn't read -
despite the fact that the poster only considered immediate
consumption, and not the increased downhill speeds and its
implications if the coast is continued on the flat or near-flat areas
following the slope.
I'm intrigued though, by your asertation that being in neutral puts
INCREASED wear on a transmission, since it was my understanding that
since it would ahve no load, and not be spun beyond the rated ranges
(in all probability slowly, depending on gearbox design), that it
wouldn't increase wear, but instead decrease it.
for the clutch packs, slipping in & out of neutral is more use than they
would experience in coasting, hence it can cause more wear. less of a
deal on the honda, and completely irrelevent in the face of the safety
arguments however! either way, there's no justification for coasting in
Whilst yes, that was the case in the 60s, not since the late 70s at
the latest has this even been an issue. A semi, comming down a
mountain, yes, a car down a hill, no. Keep with the times, and stop
with the decades old misinformation please.
it's not misinformation, it's dead accurate. brakes linings /do/ over
heat, brake lines fail, brake fluids boil, speeds can become excessive,
and you are not in full control of the vehicle in the event you need to
make any evasive manoevers. it's bad for the transmission too. do not
ever coast in neutral down a hill! /EVER/!
good comparison! but here's the difference: i don't care if he wastes
his money on excessive oil changes. really. i /do/ however care if his
willful ignorance affects /my/ safety on the road. if he careens out of
control onto /my/ side of the freeway and hits /my/ car because he's
been coasting in neutral and has lost control because his brakes are
toasted, he'd better make sure he can run faster than me, because i
/will/ be upset.
For this to work as you say, you'd need the following to happen
badly ventilated/cooled brakes.
constant application of brakes
weakened brake lines
under-spec brake fluid
Any of these would occur in any sudden deceleration from a high speed
(such as an emergency stop on the highway) and be in all probablility
more fatel then.
Modern brakes are designed to cope with small aplication loads for
longer periods of time. Many car manufacturers do these kinds of
manouvers as tests in their brake systems, to prevent precisely this
from happening. /whats more, its the very first fade test. Were you
then to take the car on a long winding downhill run from the mountains
you'd have a lot more heat buildup in your brakes, and a lot greater
application of wear, having heaier repeated applications of the
brakes, with a lower ventilation speed.
You're also on the assumption tha when coasting, people ride the brake
instead. you know, i've never done that. if i coast, i don't then ride
the brake, instead i'll make a check application, every so often.
As for the 'not in full control' argument, again, thats from the 50's
and 60's before the advent of the nice modern synchromesh. For an
avoidance measure, engine power or no will make no difference. For
stopping, your braking speed is limitedby the static friction lmiit of
the vehicles tyres. In fact, you're not having to brake the rotational
inertia of the engine and connected gearbox componants, so you're
ahead there too. The only way i can see the engine being of any
benefit is if you ahve to go FASTER, or a 90dergee+ oversteer
situation, but in that case, you'd probably want to change from a
cruising gear in any case.
Regardless, I'm sure we'll be able to go around in circles like this,
each counter-claiming the other. Instead, i'll send an email over to
see if Mythbusters will take a look at it.
1. all brakes heat on application. that's fundamental fact. if you're
dissipating /all/ your forward energy through the brakes and are not
using engine braking because you are in neutral, the brakes will heat
more!!! that's fact!!!
2. you can easily have constant application of brakes. you're never
going to have road conditions that just happen to suit you!
3. brake lines deteriorate with age! fact.
4. brake fluid absorbs water from the air. it starts to degrade the
moment you open the bottle. fact.
you don't know what you're talking about. any brake fades as a function
of temperature. temperature is a function of the speed you want to turn
into kinetic energy. any form of stop start driving, regardless of
hills, heats brakes. period.
dude, apart from the fact that coasting is illegal, you're also
indicating you don't have the vehicle under proper control.
eh? what has synchromesh got to do with it? that's utterly irrelevant.
but engine braking does!!! that's why automatics down-shift - for
engine braking and safety.
only if the brakes can supply sufficient friction. if they're toast,
you can have the best tires in the world, but they won't mean a damned
thing to stop you running into that kid that's just kicked their ball
into the road.
what planet are you on??? look up engine braking on google. truck
manufacturers invest millions in engine braking technology because its
so effective AND SAFE BECAUSE IT DOESN'T OVERHEAT BRAKES.
be my guest. geeze. i can maybe understand ignorance as an excuse if
the engineering is not understood, but using it as an excuse against the
law??? buddy, you take the prize!
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