Use for questions related to fuel economy.

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10
votes
2answers
298 views

40MPG at 100MPH?

Around 1987-1988 I had a Ford Fiesta/Festiva. I was in the Army and regularly made weekend trips, driving from southern California to Central Washington a trip of about 1200 miles. I would leave in ...
3
votes
3answers
24 views

Air/Fuel ratio at 3%-5% of throttle position (closed throttle)

Question about standard car with ECU controlled injection: Does the ECU still inject some fuel if my engine has higher revs than idle speed and throttle is closed (foot off)? As much as I know (I've ...
9
votes
1answer
245 views

Does leaving the choke closed increase fuel consumption

I ran out of fuel using my outboard engine the other day, when I had checked the tank beforehand and thought I saw plenty of fuel. I had forgotten to open the choke for twenty minutes or so. My ...
3
votes
0answers
50 views

What's the most efficient way to manually hold a specific speed?

I noticed that my new car is by activated cruise controll at lets say 50 km/h handling this speed by displaying an current consume of 1.8~2.4 l/100km, while when I'm trying to find the required ...
3
votes
0answers
41 views

Decreased MPG, clicking sound when pressing accelerator

Over the past week, the MPG on my car has gone down significantly, about 3-4 MPG. My driving habits have not changed. In the meantime, there is a distinct "pneumatic" clicking sound whenever I press ...
3
votes
1answer
43 views

Why does the engine have lesser pulling strength when the fuel in the tank is lesser?

I've noticed a difference that when the fuel in the tank is low, it takes a bit more time for the bike to accelerate to a higher speed than if the fuel tank is mid level or full. Same thing said by a ...
6
votes
3answers
248 views

Tapping into the on-board computer

I'm thinking of replacing my car's radio panel with a custom built Raspberry Pi device, something like this device. However, it's usefulness would be much larger, if I could get information from the ...
3
votes
3answers
140 views

Percent of Air and Fuel used for Combustion

I've had this question for a long time. I know the percent will differ based upon the throttle position and will be either by stoichiometric ratio or rich mixture. The stoichiometric ratio (AFR) ...
0
votes
2answers
78 views

Do Front-Wheel Drive cars consume less fuel than Rear-Wheel Drive cars? [closed]

As physics suggests it's more convenient, and thus less energy consuming, to pull a load than to push it. Having said that in a similar situation when two cars are the same in terms of weight, engine, ...
10
votes
6answers
1k views

Can a car AC unit be run on just the car battery?

This might be a silly question but I was wondering if a car AC unit be run off entirely on battery or alternator? As this could help in Preventing power loss during important times such as ...
6
votes
2answers
119 views

Does starting and stopping the engine lots over a short period of time in a non start-stop car damage anything? [duplicate]

In my 2003 Opel Agila 1.2, I try to save fuel and stop the engine manually (by turning the key) when in traffic or waiting at traffic lights etc. Sometimes when in traffic I can stop and start my ...
6
votes
3answers
218 views

Optimal acceleration for automatic transmission? [closed]

In a car with automatic transmission, what's the best way to accelerate so as to minimize fuel consumption? Assume I'm not going to change the gears manually. Note that I'm also considering non-flat ...
20
votes
6answers
1k views

Will higher octane fuel improve towing power?

According to Will higher octane fuel improve gas mileage? higher octane fuel does NOT notably improve fuel efficiency. Will higher octane fuel, increase power while towing? I looked online and ...
4
votes
1answer
59 views

How can vehicles run on E?

Sorry if this topic is too open ended I'm new to this site. I am studying engines and how they work and I keep wondering, how do cars with no gas still manage to run for a few extra miles? If you ...
26
votes
6answers
6k views

Do cars consume less fuel when in Neutral? [duplicate]

Imagine we're going down a hill and we're driving a manual car. There are two situations: If I put my car in neutral it will go downhill without any need for the injector to squirt fuel into the ...
0
votes
1answer
86 views

How can I calculate MPG using an OBD-II Device

OBD-II provide following readings Mass Air Flow (PID 0166) Fuel–Air commanded equivalence ratio (0144) Can these be used to calculate the actual fuel consumed? Is the output correct?
8
votes
2answers
798 views

For how long should I idle at a stop?

As I approach a stretch of road that has been single-laned due to roadworks, the sign-flipper spins the sign to STOP. Having been through these roadworks before, I know I'll probably be waiting at ...
1
vote
0answers
30 views

Opel Corsa lite 1.4 2002

After reconditioning cylinder head and skimming. Fitting new hydraulic lifters and rockers, find no compression on engine once oil reaches the lifters compression disappears. Tried reducing length ...
3
votes
1answer
49 views

Can we determine the Cleaning Requirement of Air Filter Using OBD

Many a times, the dealer guy says that the unclean air filter consumes more fuel as compared to clean. So, my question is, is this really related to air filter? If yes, can we determine the case using ...
7
votes
0answers
109 views

fuel consumption is high

My VW Golf 3 is over-consuming fuel, I use 10 liters for 45km, My mechanic ask me to change the automatic gear-box because it is not selecting gear above gear 3 I change the automatic gear-box but ...
7
votes
2answers
116 views

Driving slower at low constant rpms or driving fast to get to destination faster, which saves more gas?

As the question title says. I am a new driver and I understand that driving at higher RPMs can burn more gas faster. However getting to a destination longer would mean you were spending gas at a ...
15
votes
6answers
2k views

Why or why not increase engine efficiency by running the car “fuel-lean” (using a turbo or supercharger)?

Everyone wants their cars to use less fuel, right? I read the following passage about running the car fuel lean from this website: Run the engine fuel-lean, that is, use excess air. It is well ...
6
votes
1answer
184 views

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. ...
5
votes
1answer
228 views

2008 Toyota Corolla 141 Fuel Consumption Too High

I recently got a Toyota Corolla 141. The petrol consumption is too bad. It does only around 7.5-8 Km/l. Could you please let me know the reason behind this ? I was told that the vehicle is too heavy ...
14
votes
4answers
1k views

What makes two-stroke engines less fuel-efficient than four-strokes?

It is a commonly-held belief that two-stroke engines are less fuel-efficient than four-stroke engines, and some example BSFC figures appear to confirm this as well. But what is it that causes two-...
4
votes
1answer
141 views

Calculating AFR using injector flow rate and mass air flow

Is injector flow rate = Mass fuel flow? If so then AFR = MAF/Injector flow rate. Can someone please confirm this?
6
votes
1answer
46 views

1967 Ford F100 miles per gallon

I plan on getting an 1967 ford f100 and saw that the gas mileage isn't the best on these trucks. The certain truck I have my eye on has a V8 5.8L engine and was wondering if more liters in the engine ...
5
votes
0answers
511 views

What causes more gas consumption - Idling with AC or Heat? [duplicate]

So I have begun doing some research on the effects of idling. So my question is, does idling with the AC or heater on affect how much gas is given off? If possible, please give the percent of extra ...
5
votes
1answer
42 views

Fuel system question

See red arrow in the image. I place fuel additive in my car, all of the additives went into that pipe (in the red arrow image) because i didnt know how to place it. Will it still work? or just a waste?...
5
votes
1answer
49 views

Why does my 2005 Mitsubishi Pajero use excessive amounts of fuel?

I have a Wagon with excessive fuel consumption. It's using 30 litres of petrol per 100 ks. I have seen many mechanics who can't find the problem. I know it has good intake and no exhaust problems. ...
1
vote
0answers
35 views

fuel consumption in CR-V 2007

lately I found my car consuming more fuel than usual,it was doing 8 liters per 100km,then it raised to 12 liters per 100km,I asked its agency to check for the problem,they found nothing unusual,after ...
6
votes
4answers
231 views

Cheap vs Expensive Fuels [closed]

What is the difference between the cheapest fuels in a place like Tesco's and the 'high quality', highly priced competitors? Is there actually any noticeable difference in available power, engine ...
7
votes
1answer
54 views

Gasoline grade manufacturer recommends vs what was used during testing

Toyota recommends to use regular(87) grade of gasoline, but tested cars with the gasoline grade 91(see user manual). Somebody know why they recommend to use grade 87 if they did not tested cars with ...
5
votes
2answers
70 views

What senses/controls how much fuel is spent for a given RPM?

When maintaining a constant speed on the highway whether up, down or flat the engine still has the same RPM (assuming the incline is shallow enough not to require a gear change) - common sense would ...
6
votes
1answer
191 views

Why vehicles use fuel and how can fuel economy be improved?

Why vehicles use fuel? Where does the energy in the fuel go? Vehicle fuel efficiency is continuously increasing. Why is this the case? What technologies car manufacturers are using to improve fuel ...
7
votes
3answers
193 views

Will an old engine have worse fuel efficiency than a new engine?

I have a gasoline-engine car that is four and half years old and has been driven for 60 000 kilometers. I have noticed that the fuel efficiency is not what it was when the car was new. However, I ...
3
votes
2answers
142 views

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 ...
2
votes
1answer
114 views

Fuel consumption is bad

I currently own a 2010 Honda Civic 1.8L and a 2012 Honda Jazz(Philippines) / Fit (USA and Japan) 1.5L. I just purchased a second hand Jazz/Fit about 2 weeks ago and the mileage is 32xxx. Btw we use ...
5
votes
2answers
349 views

Is manual start/stop good on older cars?

I have an old car (but with electronic injection) that predates by far start/stop systems which are used nowadays to save fuel (turning off the engine brings savings after 3-5 seconds, see Calculating ...
4
votes
1answer
239 views

2014 Nissan Pathfinder decreasing fuel economy

I purchased a slightly-used 2014 Nissan Pathfinder in January 2015 and have been using it to commute to work (almost exclusively, with the exception of the occasional trip). It currently has 41,000 ...
3
votes
2answers
58 views

1980 Chrysler LeBaron Failed Emissions Test

My 1980 Chrysler LeBaron (V8 318ci) just failed an emissions test. I'm coming from a state without emissions testing to a state that requires it. Specifically, the only part that failed was the ...
9
votes
6answers
643 views

Fuel consumption at same speed of different engine

I am wondering why two car running at 100 km/h for example with a 100 hp consume less fuel that an engine of 300hp. Even if I take a supercar lighter and more aerodynamics it will consume more. But ...
4
votes
2answers
65 views

Fuel Economy Gauge Modification

I have a little digital screen in my dash that re-evaluates my average fuel consumption (L/100km) every thirty seconds. How can I modify this to increase the reporting frequency? Preferably, at least ...
4
votes
3answers
146 views

How would a bad barometric reading affect gas mileage?

My wife drives an '08 Hyundai Azera Limited 3.8L with ~79k miles. Over the past few months she has been complaining that the gas mileage has gone down. Normal around town driving was getting us ~19.6 ...
2
votes
2answers
115 views

Fuel gauge not accurate

This does not always happen but it has happened twice in last 6 months. My fuel gage is accurate most of the times but these two times it was showing that there is 10-15% gas in my tank but my car ...
1
vote
3answers
388 views

How to calculate fuel consumption?

If i know the rpm at which the (tachometer indicated) engine is running and the current speed and the engine capacity is there a where to calculate the fuel consumption of the engine? Need not be a ...
6
votes
3answers
430 views

Does Max Power RPM Equal Max FE?

I was looking over the specs for a 98 Mazda 626 2L and noticed that it says the max power is at 5500 RPM. Will the Max Power RPM also be the RPM at which the engine is most efficient assuming you'...
4
votes
0answers
40 views

Integrating Fast OBD Readings and GPS

I'm working on a project to look at fuel consumption on different roads and I need the OBD reader to log the GPS coordinates every time it takes a reading. I'm looking at instantaneous fuel ...
5
votes
3answers
729 views

For 2 identical car models, 1 being cabriolet, which consumes less fuel?

What is the effect on car fuel consumption of having a roof or not? I guess it may depend on the car model, but generally, considering common commercial cars, which setting saves more fuel?
2
votes
2answers
356 views

Mileage varies by driving at different speeds

I drive my car a lot. I do lot of experiments with speeds while driving. Following are my observations: Driving at 60 - 70 km/h gives maximum mileage Driving at 70 - 90 km/h gives good mileage ...