Motor Vehicle Maintenance & Repair Stack Exchange
Motor Vehicle Maintenance & Repair Stack Exchange

Questions tagged [efficiency]

Generally speaking, the ratio of how much work a component or apparatus does to the amount of energy or power it uses.

Generally speaking, the ratio of how much work a component or apparatus does to the amount of energy or power it uses.

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Will engine braking damage my transmission? How can I tell?

I drive a manual transmission '08 Honda Fit. On my daily 17 mile commute to work, there are three long hills that I can coast down, each about a half mile long. Going down these hills, I've done two different things: I take it out of gear and let…
yhw42
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At what time of day/temperature should I refuel my vehicle?

I mean, should I refuel my vehicle in the morning? The reasoning is simple, in the morning the temperature is low and the density of the fuel would be higher and I get more energy per litre(or whatever metric system you use). But in afternoon, or…
RogUE
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What causes a 20% difference in fuel economy between winter and summer?

I've been keeping track of the fuel my car, a Ford Fiesta Ecoboost 100 hp, uses since the day I got it. In the last three years I've owned it, I've noticed a large (>20%) difference in fuel consumption between driving in winter and driving in…
Ives
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How much can sub-optimal octane affect efficiency or power?

Suppose a production fuel-injected engine is tuned for 93 octane fuel. As I understand it, the engine can still run on lower-octane (i.e., less knock-resistant) fuel, but it will pull timing to avoid knocking. In effect, on lower octane gasoline…
feetwet
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Are fuel efficiency charts available for mainstream engines?

I came across this page, which is quite a bit too mathematical for me to follow, and I think is purely theoretical (ie. not based on experimental evidence of a specific engine). It produces the below charts. If I am reading this right, this…
User65535
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Alternative fuel consumption metric to MPG to measure actual engine efficiency?

MPG is all very well and good, considering that most people that are concerned about their fuel consumption tend to want to get as many miles as they can out of it before they need to fill up again. However, I was stuck in traffic recently averaging…
Max Goodridge
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Will I be better off turning the start stop function off?

I drive a 2017 VW Polo 1.0L. I use the car for primarily short journeys with the occasional motorway run. The car has a start stop function but I am skeptical of the benefits. Will it be a useful feature for somebody who does mostly short journeys…
Joe
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Is it more efficient to drive with the windows down or the AC on?

When driving, is it more efficient (in terms of gas consumed) to use the air conditioner, or to drive with all of the windows down? While the air conditioner reduces efficiency through drag on the engine, driving with the windows down increases air…
cawwot
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Results surprising said lab reporter of emission testing on Toyota Qualis Diesel 4 wheeler on AVL DiTest MDS 205

I got emissions of Toyota Qualis Diesel car tested with the AVL DiTest MDS 205, the result sheet had following columns rpm, temp, secs, CO(%vol.), CO corrected, CO2(% vol.), HC(ppm),HC corrected(ppm),Dilution, O2(%vol.), Lambda, NOx(ppm), AFR. I am…
D_batmaniac
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Is there correlation between fuel efficiency and preferred gear at certain speed?

It may very well be just my imagination, but 3 months ago i decided i can do 30 miles per hour on 3rd gear and not shift to 4th. It didn't seam like the engine was under any extra stress or anything, it was doing 2400 rpm (an around 1850 on 4th).…
Иво Недев
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What non-driver, non-terrain factors can affect vehicle miles per gallon?

I've been tracking the mileage on my 2015 VW Golf (a non-intercooled turbo, but not diesel, thank goodness). Of course, my driving habits and highway/city balance influence things greatly, but beyond that the data seems to show significant and…
Daniel Griscom
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Does the size of engine cylinder affect the efficiency?

I mean that, if cylinder have a design in which piston can change its working area alternate. Is there any chance to affect the burning ratio in loss or profit to efficiency?
Himanshu solanki
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Is Tom Ogle's 100+mpg engine actually feasible?

I've just read about Tom Ogle, an inventor who claims to have built an fuel injection system that can achieve 100+ mpg and has apparently proven it, before dying in suspicious circumstances. From a technical point of view, is this even feasible?…
André Borie
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Fuel Consumption Paradox

I've been trying different driving styles for a while now, in an effort to reduce my fuel economy and tank range. I've found that I get the best results when racing around, as opposed to driving particularly slow or carefully. What's going on?…
voices
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What would be better for an engine driving at 60mph or 70mph? I wish to get the most miles out of my engine?

At 60mph my engine revs at 2800RPM and at 70 it's 3200RPM. My qustion is which condition would give the most miles from my engine.
ceefax12
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