For those who want to improve their fuel economy, or are wondering why it's not as good as it ought to be...

learn more… | top users | synonyms

3
votes
1answer
120 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 ...
4
votes
2answers
153 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 ...
7
votes
3answers
1k 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 ...
3
votes
2answers
82 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're ...
2
votes
0answers
20 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
1answer
273 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 ...
4
votes
2answers
189 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 ...
2
votes
2answers
670 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?
3
votes
5answers
6k views

How to save fuel on downhill slopes on a motorcycle: clutch or neutral?

I have a two wheeler i.e. bike (Honda company, four stroke) which has four gear. While driving my bike, when I come to downhill slopes, I shift the motorcycle to neutral to save the fuel. (The slopes ...
7
votes
7answers
25k views

Is the ECON button just a placebo?

I recently bought a Honda Civic that had this in the car: I have no idea what it does, and how it's supposed to help. Even Honda's website is ambiguous, just using a lot of fuzzy words to describe ...
8
votes
7answers
925 views

Is shifting to neutral on a decline more fuel efficient than keeping the gear engaged?

I always had the habit of shifting to neutral on long declines and using the brakes to slow down as needed. Intuition made me believe I'd be saving fuel as opposed to keeping a gear engaged. However, ...
2
votes
2answers
267 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 ...
2
votes
2answers
66 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
26 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
212 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
55 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
56 views

How to find the cause of sudden high fuel consumption of a motorbike?

About my bike Model: Honda CBR 250R Total Run: 35000kms Total Time: 2 years 3 months Clutch Plate changed at 30k kms after an accident Engine oil, engine oil filter and air filter changed in ...
4
votes
1answer
92 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.
6
votes
2answers
1k views

Pulsar 180 - How Can I Measure the Mileage?

Could anybody please tell me how to measure the mileage of my Pulsar 180 bike accurately? I have tried by emptying my tank. I failed miserably, and I had to take my bike walking long distance.
1
vote
3answers
558 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 ...
4
votes
5answers
27k 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 ...
11
votes
1answer
2k views

How much does spark plug gap affect fuel efficiency?

I've read conflicting reports regarding how plug gap can affect fuel efficiency. For example, I've read that too small a gap won't cause a clean burn, or that too large a gap can cause misfires due ...
3
votes
1answer
405 views

Brake Specific Fuel Consumption of 2-stroke vs 4-stroke

How much fuel do various types of engines burn per power output? I'm especially interested in naturally aspirated piston engines, and comparing two-stroke to four-stroke. The wikipedia article gives ...
1
vote
1answer
377 views

Car stalling in the morning

So I have been dealing with an elusive CE light and some shaking of my car for a while now. For a while it was just shaking occasionally, I thought it was a moisture problem, but that doesn't seem ...
2
votes
1answer
328 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
531 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 ...
2
votes
1answer
134 views

What is Total litres (reserve, usable)15 litres (3.2 litres reserve, 2 litres usable)?

I bought a new bike(Pulsar 150), and while reading its specs in the user manual i found Total litres (reserve, usable) = 15 litres (3.2 litres reserve, 2 litres usable). what does this mean, I assume ...
6
votes
4answers
4k 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 ...
6
votes
1answer
121 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
2k 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 ...
11
votes
6answers
10k 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
42 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?
16
votes
7answers
64k 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 ...
5
votes
1answer
826 views

How does ambient temperature affect engine efficiency and fuel consumption?

I remember from my physics class that the ideal-gas Carnot engine is more efficient if the temperature difference between the heat source and the thermostat ("heat recipient") is larger ...
0
votes
2answers
546 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 ...
4
votes
2answers
298 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 ...
1
vote
5answers
86 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
807 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 ...
6
votes
6answers
12k views

What can cause a car to consume more fuel?

All over my long driver career, I had 4 cars (5 years). I always compare my fuel consumption with other people who have the same car. 3 times out of 4, I found out that my cars were consuming more ...
2
votes
1answer
154 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 ...
6
votes
2answers
3k 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
222 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
2k 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
376 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
331 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
1k 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 ...
-1
votes
1answer
398 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
94 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
80 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
311 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?