Use for questions related to fuel economy.

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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 ...
6
votes
4answers
233 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
4answers
2k views

why do engines have so much unused horsepower?

I've looked at the power rating of an engine used in a Humvee (5500 lbs) and was surprised it's only ~190 horsepower, which is exceeded by many 4 door sedans. So an obvious question is why doesn't my ...
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
196 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 ...
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 ...
2
votes
1answer
120 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 ...
2
votes
1answer
389 views

KIA Sedona 2003 Diesel Intercooler Turbo Low Fuel Mileage

I have a 2003 a Kia Sedona turbo diesel 2.9L, with intercooler. I am getting 5 km per liter of diesel consumed. I also have to do oil change and ATF replacement. I got the car 3 weeks ago. What are ...
7
votes
5answers
7k views

Can I improve fuel economy by changing differential’s gear ratio?

I would like to use my Lada Niva for normal road travel, but at 3500 rpm at 100 kph it is not very fuel efficient. I don’t know what the current differential ratio is, but I assume it has been changed ...
4
votes
2answers
409 views

Loss of engine power between 2100 and 2500 RPM on humid days - 2011 Malibu

I drive a 2011 Chevy Malibu LT (4 cyl, 2.4L, 6 spd. automatic) and have been experiencing this problem for the past year and a half. Basically, whenver its hot (90f+) and humid out, my car exhibits ...
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
241 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 ...
2
votes
2answers
116 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 ...
4
votes
3answers
147 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 ...
7
votes
3answers
755 views

Calculating MPG from MAP sensor (or converting MAP data to MAF data)

My 2002 Honda Accord V6 has a Manifold Absolute Pressure sensor (MAP). I understand that this sensor gives out information in pressure units (psi or equivalent). After doing a bit of research, I ...
1
vote
3answers
398 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 ...
1
vote
4answers
782 views

Torque App Mileage reliability?

I am using an OBD-II sensor and the Andriod Torque app to look at my fuel economy and see that it shows a whopping 37 MPG for my Mazda 6, 2005 (2.3 Automatic). This seems fishy as some random googling ...
5
votes
2answers
928 views

How much fuel does it take to start an engine?

I appreciate this is a question that can't be answered in facts and figures, so I'm after a general idea. I drive a 1986 Supra, which has a modest 2.8-litre engine. I often shut the engine off while ...
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 ...
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 ...
3
votes
2answers
282 views

Why does my front wheel rotor is heating up more than rear one?

I had been facing high fuel consumption lately. To my surprise I discovered that my front wheel free rotation seems bit restrictive to my rear one even when rear wheel drags chain and two sprockets ...
2
votes
1answer
67 views

Are CO2 emissions proportional to MPG figures?

I was looking at the car tax (VED) system in the UK, as I'm considering buying a new car. I was just wondering, are CO2 emissions always proportional to the MPG figure of a car, both in theory - ...
2
votes
2answers
734 views

fuel consumption

What is the normal fuel consumption for injection type Toyota carina e 1.6 cc 4A engine? My 1995 Toyota Carina e car gives 9.5km/l in city and 12 km/l on highways. How can I increase it more? toyota ...
2
votes
1answer
179 views

Which convenience features in a car affects fuel economy?

I understand that the A/C compressor runs with the engine belt, so it will always uses some HP when engaged, therefore it will have some effect on fuel consumption. What I want to know if there are ...
4
votes
1answer
273 views

Fuel efficiency and volumetric efficiency

I was reading about the better volumetric efficiency of DOHC engines as compared to SOHC engine and was wondering if fuel efficiency is directly related to volumetric efficiency.
1
vote
3answers
2k views

Fast Idle and High Fuel Consumption

I just bought a Manual 97 Mazda Lantis 323 1.8L DOHC 16 Valve BP and I was amazed that it went through 1/4 tank gas ( about 12.5 liters or 3.3 gallons ) in one day after about 60 kilometers / 37 miles ...
5
votes
5answers
46k views

What to check if fuel consumption is too high?

I think my car is consuming much more fuel than it should, I've compared it to other versions of the same model which have more powerful engines and mine seems to be on the higher end when is supposed ...
2
votes
1answer
445 views

Changed O2 Sensor and my mileage went down

I changed the O2 sensor on my 97 Mazda 323 BA 1.8L BP DOCH Lantis and my mileage actually went down. The car had the original sensor in it, with about 200,000 kilometers on it and I replaced it with ...
7
votes
1answer
4k views

What does a healthy spark plug look like?

The spark plug pictured here: Has some black carbon on the underside of the ground electrode and has black carbon on the "base" area below the centre electrode (not pictured). Is this normal and ...
6
votes
1answer
511 views

Oily Sludge in the Intake Manifold

When taking off the throttle body to clean my IAC, I noticed that there was a thick layer of oily sludge coating pretty much everything inside the intake manifold: I have two queastions: How did ...
8
votes
2answers
3k views

Low power, bad gas mileage, smelly exhaust after engine work

My 92 Civic has had low power (need to use at least one gear lower than usual to get the same power) and has been getting bad gas mileage (15-25mpg vs 32-42 mpg usual) since I replaced the head gasket....
14
votes
6answers
14k views

How to improve fuel economy in high-mileage car?

I'm driving an 2003 Acura TL 3.2 with 177K miles on it. I bought the car with 110K miles on it. It seems to me that the car is not getting the same fuel economy that it did when I acquired it. I ...
4
votes
1answer
67 views

How is “Fuel consumption (economy) - combined” Calculated?

I have a Mazda - 323 S V (BA) - 1.8 i 16V (114 Hp) and the data sheet for it says: Fuel consumption (economy) - combined 7.9 l/100 km. How is this calculated and under what driving conditions?
19
votes
7answers
125k views

Is idling bad for your engine?

If I sit in my car for 30-40 minutes with the AC and the car idling, does that "hurt" the engine, or does it simply waste gas and pollute the air? Would it be better if I turned off the car? A ...
4
votes
2answers
2k views

How much improvement from replacing an O2 sensor?

I'm currently getting about 19.6 mpg city in my 97 Mazda Lantis 323 / Protege 1.8L. According to fuelly a car like this should be getting around 26 mpg. The car has about 127k miles on it, and I don'...
1
vote
5answers
112 views

More air pressure in tyre Vs Mileage

Whenever I inflate my tires to medium/recommended pressure the mileage is better and obviously when it is very low the mileage affected. But I want to know why my mileage affected even if I keep ...
-1
votes
2answers
1k views

Why are American cars less efficient compared to european European/Japan cars [closed]

A normal average European car has a engine with less than a 2.0 liter engine which consumes 1 litre of fuel in 18-22 km. A normal average American car has a engine at least a 2.5 liter engine and ...
2
votes
1answer
344 views

Automatic Throttle Body and TPS on a Manual

This is in continuation to my question Fast Idle and High Fuel Consumption. I just bought a Manual 97 Mazda Lantis 323 1.8L DOHC 16 Valve BP ( apparently called a Protege in the US ) which has a fast ...
8
votes
2answers
13k views

Is topping up the oil enough of an oil change?

If you use synthetic ester-based oil in a relatively new petrol engine, top it up regularly, and the engine runs very quietly and basically without any noise whatsoever (especially after another top ...
0
votes
3answers
459 views

How to increase fuel economy

What is the normal fuel consumption for carburetor type Toyota 3A engine? My 1986 Toyota Carina AT 150 car gives 11 km/l in city and 14 km/l on highways. How can I increase it more? Please advise.... ...
1
vote
4answers
5k views

Will a battery reset improve fuel consumption?

I recently bought a used 2003 Opel(Vauxhall) Astra G 1.4. I drove around 2000km's in the last few months (city and highway mixed), and I used about 200 litres of gasoline, which means a 10l/100km ...
2
votes
3answers
665 views

Is Petrol usage Proportional to Gas Pedal position

I was wondering about this the other day. Is the petrol usage in the car only influenced by the position of the gas pedal? So for example if I take my foot of the gas and coast for 30 seconds, would ...
1
vote
1answer
557 views

“Reserve” on 2009 Ford Fusion SE Range Calculator?

All, I'm trying to calibrate a smartphone fuel consumption application on my vehicle, a 2009 Ford Fusion SE with the I-4 engine. I want to get a "control" varible to compare against the mileage ...
4
votes
2answers
2k views

Car average mpg display correctness

I have been wondering about the correctness of the average MPG displays on modern cars. Mine in particular is a Renault Modus. What I did is fill the tank, drive around and then refill the tank to see ...
0
votes
1answer
763 views

Why do i have to service my gearless Honda Activa every 2 weeks

I currently own a Honda Activa which is of a 2007 make. After three years during a heavy traffic jam the conveyer belt got heated up and burnt due to continuous acceleration and braking. I got it ...
0
votes
1answer
123 views

Using narrower tyres than were fitted as standard, for reduced rolling resistance = > fuel economy

I have had several cars, which have all been "sporty", fuel economy has never been a requirement. Now it is. So I've bought a little 1.2 petrol which gives me 65mpg on the motorway/highway and 40mpg ...
0
votes
1answer
98 views

Can I install nano fuel economizer for carb type toyota 3A engine?

Can I install nano fuel economizer for carb type toyota 3A engine? Will it help to improve fuel consumption of my car without any issue?
0
votes
1answer
645 views

what is the advantage of octane 90 petrol vs octane 95? how it effect to fuel consumtion of a car? [duplicate]

i need to know about advantages of octane 90 petrol VS octane 95 or unleaded. how it effect to fuel consumption of a car?