Terrible Fuel-Efficiency - 2003 Accord

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.

John

Drewaffe wrote: I shift into Neutral and coast downhill

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It's illegal to shift into neutral when going downhill, in some juristictions. It's for a couple of good reasons. Don't do it.

'Curly'

And prey tell what ARE those reasons.

oh yeah, because you can easily ram into someones ass. :P

Wow, altitude and mountainous terrain affects gas mileage? very interesting. Who says you don't learn something new everyday?

Thanks for the info

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

fuel filter air filter plugs

at a minimum.

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.

I only know that the regular unlead gas is 86 instead of 87 in Utah and Colorado. I do not know that affects the gas mileage, also.

See, among others,

.

The lower octane gas in the Rocky Mountain states is appropriate for the altitude.

I doubt the lower octane affects fuel mileage.

"Guy" wrote

I hadn't considered that. The altitude has the same effect as not opening the throttle all the way, so lower octane works fine.

Mike

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.

you're in reformulated gas territory, which probably means lower calorie content for your gas and therefore lower mileage.

Not to mention that it will cause worse gas milage. Modern fuel-injected engines shut off fuel flow when decelerating, but have to maintain fuel flow for the engine to idle. Dan (This account is not used for email.)

Hello, 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. Jason

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.

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 neutral.

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/!

Somtimes, nothing will convince a zealot. Like the constant debate wiht those who still think they're doing their new cars a favor by changing the oil every 3,000 miles.

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.