Why Gas Mileage is SO bad?
12-26-12, 06:24 PM
#16
Hard to argue with scientific proof like that.
12-27-12, 03:22 AM
#18
The solution will not include throwing money away using premium gas, because it isn't going to help. If you don't believe me, fine, check for yourself. Run the car down as low as you can, then fill it with premium. Putting $10 worth in isn't going to give you accurate results, because the octane of the resulting mix in your tank will be a weighted average of what was already in the tank and what you put in. Reset your trip odometer and drive it as you usually do. If the car is an 05, it will have an average mpg display, so reset that too. Run through the whole tank and see what you get. Ideally, you'd want to repeat that a couple of times to get a good baseline. Then do the same thing using regular. Or, you can save yourself some money and take my word for it, your choice.
12-27-12, 10:38 AM
#19
Hello,
Wonder if anyone can share your experience & knowledge for my issue -
My 2005 ES330's fuel cunsumption is about 12-14 mpg, which is really bad. I tried everything I could such as cleaning MAF sensor, replacing air filter, adding engine cleaner addtive. Unfortunately nothing is improved.
In addtion, I don't think gas tank leaks becasue I never smell gas when it parks in garage. However, I do smell gas from muffler pipe when the car is started.
Thanks in advance for your help!
Gary
Wonder if anyone can share your experience & knowledge for my issue -
My 2005 ES330's fuel cunsumption is about 12-14 mpg, which is really bad. I tried everything I could such as cleaning MAF sensor, replacing air filter, adding engine cleaner addtive. Unfortunately nothing is improved.
In addtion, I don't think gas tank leaks becasue I never smell gas when it parks in garage. However, I do smell gas from muffler pipe when the car is started.
Thanks in advance for your help!
Gary
I'll throw in my $.02 for what it's worth. Are you manually calculating the MPG or are you going by the average MPG as shown on the dashboard? The reason I ask is, since it's winter, if you let the car idle a lot, it really ruins that average. For example, my car is reporting approx. 18 MPG right now (average), probably because I let it idle a while in the morning. But in reality, I am getting about 380 miles out of tank (24+ MPG combined) when I calculate at fill-ups. That is with mixed city/highway driving. Also reset the AVG MPG once in a while, especially if you've been idling a lot.
12-28-12, 09:02 AM
#20
On the chance you're still checking this thread:
The first thing I'd do is make sure you really know what mpg you're getting, since your numbers sound a little suspect. You said you were getting 400+ miles on the hiway, but getting only 22-23 mpg. 400 miles at 22 mpg would be 18.2 gallons out of an 18.5 gallon tank, and 23 would be 17.4 gallons. If you're really running it down that far you're braver and more foolish than I. I think you're probably getting 26-27 mpg, which is about right. And it would be nearly impossible tor you to get 12 mpg combined unless you spent an awful lot of time idling, warming the car up or stuck in traffic. Also, you didn't reply on how long this has been going on, whether it has always been that bad or if it is a recent development.
So, fill it up, reset the trip odometer and the avg mpg display. Drive the car as you normally do. When you fill up next, keep the receipt and write down how many miles you've driven and the avg mpg indicated, then reset the trip odo and avg mpg display, and repeat. Divide miles driven by gallons purchased to get actual mpg. I've found that the avg mpg display in mine is usually less than 3% off in either direction, but you should compare the actual vs the displayed to get an idea of how accurate your display is. It's best to do this over a couple of tanks of fuel at least, since that will help average out any variance in how much you actually put in to fill it, and some tanks might have a little more city vs hiway driving and vice versa. Do not reset the avg mpg display in between fill ups, it becomes meaningless then. It then just shows what the mpg has been since the last reset and you can't compare it to what the actual calculated mpg for the entire tank is.
Now, for a few reasons that your fuel economy might be worse than normal:
1) Winter blend fuel contains around 2% less energy than summer blend, so you should lose around 2% in mpg just from that change.
2) Check your tire pressures, lower outside air temps will also lower tire pressure, and under inflation will cost you some fuel economy. I think Lexus recommends around 29 psi, but I put 32 in mine. Do not think that if a little more pressure is good, a lot more is better. There is a point of diminishing returns, and over inflating can lead to excessive tire wear, reduced traction, and excessively harsh ride.
3) Colder temperatures result in longer warmup times, and the engine runs richer than normal during warmup. Also, transmission fluid, engine oil, and differential lube takes longer to warm up and will be thicker and therefore result in more resistance and will require more engine power to overcome. If you make short trips or make several stops, the engine and drivetrain may never fully warm up and reach it's most efficient operating temperature. Heater and defroster fans, heating elements in windows, and more use of headlights also consume energy and so decrease fuel economy. It also creates greater tire slippage if the roads are icy and will increase tire drag.
4) Colder air is more dense, so at highway speeds it takes more energy to push the car through the air than it does through warmer, less dense air.
5) Letting the car idle to warm up. When you're sitting still, you're getting 0 mpg, so the best thing to do is let it idle for 15-20 seconds to get the oil flowing and then start driving, gently, until you get some heat in the engine. With no load, the engine will take longer to warm up, so it will warm up faster and you won't spend minutes burning fuel and going nowhere if you start driving immediately.
The first thing I'd do is make sure you really know what mpg you're getting, since your numbers sound a little suspect. You said you were getting 400+ miles on the hiway, but getting only 22-23 mpg. 400 miles at 22 mpg would be 18.2 gallons out of an 18.5 gallon tank, and 23 would be 17.4 gallons. If you're really running it down that far you're braver and more foolish than I. I think you're probably getting 26-27 mpg, which is about right. And it would be nearly impossible tor you to get 12 mpg combined unless you spent an awful lot of time idling, warming the car up or stuck in traffic. Also, you didn't reply on how long this has been going on, whether it has always been that bad or if it is a recent development.
So, fill it up, reset the trip odometer and the avg mpg display. Drive the car as you normally do. When you fill up next, keep the receipt and write down how many miles you've driven and the avg mpg indicated, then reset the trip odo and avg mpg display, and repeat. Divide miles driven by gallons purchased to get actual mpg. I've found that the avg mpg display in mine is usually less than 3% off in either direction, but you should compare the actual vs the displayed to get an idea of how accurate your display is. It's best to do this over a couple of tanks of fuel at least, since that will help average out any variance in how much you actually put in to fill it, and some tanks might have a little more city vs hiway driving and vice versa. Do not reset the avg mpg display in between fill ups, it becomes meaningless then. It then just shows what the mpg has been since the last reset and you can't compare it to what the actual calculated mpg for the entire tank is.
Now, for a few reasons that your fuel economy might be worse than normal:
1) Winter blend fuel contains around 2% less energy than summer blend, so you should lose around 2% in mpg just from that change.
2) Check your tire pressures, lower outside air temps will also lower tire pressure, and under inflation will cost you some fuel economy. I think Lexus recommends around 29 psi, but I put 32 in mine. Do not think that if a little more pressure is good, a lot more is better. There is a point of diminishing returns, and over inflating can lead to excessive tire wear, reduced traction, and excessively harsh ride.
3) Colder temperatures result in longer warmup times, and the engine runs richer than normal during warmup. Also, transmission fluid, engine oil, and differential lube takes longer to warm up and will be thicker and therefore result in more resistance and will require more engine power to overcome. If you make short trips or make several stops, the engine and drivetrain may never fully warm up and reach it's most efficient operating temperature. Heater and defroster fans, heating elements in windows, and more use of headlights also consume energy and so decrease fuel economy. It also creates greater tire slippage if the roads are icy and will increase tire drag.
4) Colder air is more dense, so at highway speeds it takes more energy to push the car through the air than it does through warmer, less dense air.
5) Letting the car idle to warm up. When you're sitting still, you're getting 0 mpg, so the best thing to do is let it idle for 15-20 seconds to get the oil flowing and then start driving, gently, until you get some heat in the engine. With no load, the engine will take longer to warm up, so it will warm up faster and you won't spend minutes burning fuel and going nowhere if you start driving immediately.
12-31-12, 10:56 AM
#21
if you really really want an accurate calculation, buy a scangauge or get an obd2 scanner with bluetooth/etc and some software that will measure mpg and data log that over a week or two of normal driving. then compare that to what is official for the car, usually on fuely or fueleconomy.gov. that should give you an idea of how far off you are really accurately.
i lose about 2-3 mpg in winters btw. my 97 gives me 23 mph combined in summer, 21mpg in winter, the best i have even got is about 27/28 on the highway
i lose about 2-3 mpg in winters btw. my 97 gives me 23 mph combined in summer, 21mpg in winter, the best i have even got is about 27/28 on the highway
01-07-13, 05:57 AM
#22
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I tested twice on highway, one was for Boston and the other was for Virginia, of course from Ontario. Pure highway driving, both gave me about 25mpg. Unfortunately it has been giving me about 13mpg for local driving ( maybe, 30% is on highway). It is not a recent change.
01-07-13, 06:01 AM
#23
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01-07-13, 06:03 AM
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mine is 2005 ES330, 6 cylonder. Premium is always used.
01-07-13, 06:22 AM
#25
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Hey Gary,
I'll throw in my $.02 for what it's worth. Are you manually calculating the MPG or are you going by the average MPG as shown on the dashboard? The reason I ask is, since it's winter, if you let the car idle a lot, it really ruins that average. For example, my car is reporting approx. 18 MPG right now (average), probably because I let it idle a while in the morning. But in reality, I am getting about 380 miles out of tank (24+ MPG combined) when I calculate at fill-ups. That is with mixed city/highway driving. Also reset the AVG MPG once in a while, especially if you've been idling a lot.
I'll throw in my $.02 for what it's worth. Are you manually calculating the MPG or are you going by the average MPG as shown on the dashboard? The reason I ask is, since it's winter, if you let the car idle a lot, it really ruins that average. For example, my car is reporting approx. 18 MPG right now (average), probably because I let it idle a while in the morning. But in reality, I am getting about 380 miles out of tank (24+ MPG combined) when I calculate at fill-ups. That is with mixed city/highway driving. Also reset the AVG MPG once in a while, especially if you've been idling a lot.
When fuel needs to be refilled up:
1. reset the trip-A to zero;
2. and refill the fuel fully.
When fuel needs to be refilled up for following time:
1. refill fuel fully again, and read how many gallons refilled;
2. also read the milleage of the trip-A since last fuel refill.
Therefore, the gallons of gas refilled (2nd time) is the gas consumption of the trip-A.
Thanks,
Gary
01-07-13, 06:41 AM
#26
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On the chance you're still checking this thread:
The first thing I'd do is make sure you really know what mpg you're getting, since your numbers sound a little suspect. You said you were getting 400+ miles on the hiway, but getting only 22-23 mpg. 400 miles at 22 mpg would be 18.2 gallons out of an 18.5 gallon tank, and 23 would be 17.4 gallons. If you're really running it down that far you're braver and more foolish than I. I think you're probably getting 26-27 mpg, which is about right. And it would be nearly impossible tor you to get 12 mpg combined unless you spent an awful lot of time idling, warming the car up or stuck in traffic. Also, you didn't reply on how long this has been going on, whether it has always been that bad or if it is a recent development.
So, fill it up, reset the trip odometer and the avg mpg display. Drive the car as you normally do. When you fill up next, keep the receipt and write down how many miles you've driven and the avg mpg indicated, then reset the trip odo and avg mpg display, and repeat. Divide miles driven by gallons purchased to get actual mpg. I've found that the avg mpg display in mine is usually less than 3% off in either direction, but you should compare the actual vs the displayed to get an idea of how accurate your display is. It's best to do this over a couple of tanks of fuel at least, since that will help average out any variance in how much you actually put in to fill it, and some tanks might have a little more city vs hiway driving and vice versa. Do not reset the avg mpg display in between fill ups, it becomes meaningless then. It then just shows what the mpg has been since the last reset and you can't compare it to what the actual calculated mpg for the entire tank is.
Now, for a few reasons that your fuel economy might be worse than normal:
1) Winter blend fuel contains around 2% less energy than summer blend, so you should lose around 2% in mpg just from that change.
2) Check your tire pressures, lower outside air temps will also lower tire pressure, and under inflation will cost you some fuel economy. I think Lexus recommends around 29 psi, but I put 32 in mine. Do not think that if a little more pressure is good, a lot more is better. There is a point of diminishing returns, and over inflating can lead to excessive tire wear, reduced traction, and excessively harsh ride.
3) Colder temperatures result in longer warmup times, and the engine runs richer than normal during warmup. Also, transmission fluid, engine oil, and differential lube takes longer to warm up and will be thicker and therefore result in more resistance and will require more engine power to overcome. If you make short trips or make several stops, the engine and drivetrain may never fully warm up and reach it's most efficient operating temperature. Heater and defroster fans, heating elements in windows, and more use of headlights also consume energy and so decrease fuel economy. It also creates greater tire slippage if the roads are icy and will increase tire drag.
4) Colder air is more dense, so at highway speeds it takes more energy to push the car through the air than it does through warmer, less dense air.
5) Letting the car idle to warm up. When you're sitting still, you're getting 0 mpg, so the best thing to do is let it idle for 15-20 seconds to get the oil flowing and then start driving, gently, until you get some heat in the engine. With no load, the engine will take longer to warm up, so it will warm up faster and you won't spend minutes burning fuel and going nowhere if you start driving immediately.
The first thing I'd do is make sure you really know what mpg you're getting, since your numbers sound a little suspect. You said you were getting 400+ miles on the hiway, but getting only 22-23 mpg. 400 miles at 22 mpg would be 18.2 gallons out of an 18.5 gallon tank, and 23 would be 17.4 gallons. If you're really running it down that far you're braver and more foolish than I. I think you're probably getting 26-27 mpg, which is about right. And it would be nearly impossible tor you to get 12 mpg combined unless you spent an awful lot of time idling, warming the car up or stuck in traffic. Also, you didn't reply on how long this has been going on, whether it has always been that bad or if it is a recent development.
So, fill it up, reset the trip odometer and the avg mpg display. Drive the car as you normally do. When you fill up next, keep the receipt and write down how many miles you've driven and the avg mpg indicated, then reset the trip odo and avg mpg display, and repeat. Divide miles driven by gallons purchased to get actual mpg. I've found that the avg mpg display in mine is usually less than 3% off in either direction, but you should compare the actual vs the displayed to get an idea of how accurate your display is. It's best to do this over a couple of tanks of fuel at least, since that will help average out any variance in how much you actually put in to fill it, and some tanks might have a little more city vs hiway driving and vice versa. Do not reset the avg mpg display in between fill ups, it becomes meaningless then. It then just shows what the mpg has been since the last reset and you can't compare it to what the actual calculated mpg for the entire tank is.
Now, for a few reasons that your fuel economy might be worse than normal:
1) Winter blend fuel contains around 2% less energy than summer blend, so you should lose around 2% in mpg just from that change.
2) Check your tire pressures, lower outside air temps will also lower tire pressure, and under inflation will cost you some fuel economy. I think Lexus recommends around 29 psi, but I put 32 in mine. Do not think that if a little more pressure is good, a lot more is better. There is a point of diminishing returns, and over inflating can lead to excessive tire wear, reduced traction, and excessively harsh ride.
3) Colder temperatures result in longer warmup times, and the engine runs richer than normal during warmup. Also, transmission fluid, engine oil, and differential lube takes longer to warm up and will be thicker and therefore result in more resistance and will require more engine power to overcome. If you make short trips or make several stops, the engine and drivetrain may never fully warm up and reach it's most efficient operating temperature. Heater and defroster fans, heating elements in windows, and more use of headlights also consume energy and so decrease fuel economy. It also creates greater tire slippage if the roads are icy and will increase tire drag.
4) Colder air is more dense, so at highway speeds it takes more energy to push the car through the air than it does through warmer, less dense air.
5) Letting the car idle to warm up. When you're sitting still, you're getting 0 mpg, so the best thing to do is let it idle for 15-20 seconds to get the oil flowing and then start driving, gently, until you get some heat in the engine. With no load, the engine will take longer to warm up, so it will warm up faster and you won't spend minutes burning fuel and going nowhere if you start driving immediately.
Thanks for your comments and your technical recommendations.
WRT mpg calculation, I am very sure my calculation is very accurate. As I explained in another reply, I never read mpg from dashboard, but manually calculate it. I have noticed this issue for a while (1 year), and tested many times when it was in summer or winter.
I believe there is somethings to do with mechanism, but don't know how.
Gary
01-09-13, 04:15 AM
#27
another possibility, and this is just a possibility is that there isnt enough compression in your engine? if you had a timing belt change recently and it wasnt set right, OR there is a loss of compression somewhere that is also known to cause bad mileage. just some options to consider.
are you oil changes frequent and do you use synthetic too?
are you oil changes frequent and do you use synthetic too?
01-14-13, 05:56 AM
#28
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another possibility, and this is just a possibility is that there isnt enough compression in your engine? if you had a timing belt change recently and it wasnt set right, OR there is a loss of compression somewhere that is also known to cause bad mileage. just some options to consider.
are you oil changes frequent and do you use synthetic too?
are you oil changes frequent and do you use synthetic too?
I didn't have a timing belt change recently, the problem is not recent either. Actually, more technical issue is my concern like timing belt and unsufficient engine compression. Do you have any suggestion for this? like how to check timing belt? how to check engine compression?
Gary
01-14-13, 11:22 AM
#29
Thank you MrShim78 for your comments!
I didn't have a timing belt change recently, the problem is not recent either. Actually, more technical issue is my concern like timing belt and unsufficient engine compression. Do you have any suggestion for this? like how to check timing belt? how to check engine compression?
Gary
I didn't have a timing belt change recently, the problem is not recent either. Actually, more technical issue is my concern like timing belt and unsufficient engine compression. Do you have any suggestion for this? like how to check timing belt? how to check engine compression?
Gary
01-15-13, 02:32 PM
#30
come on folks 10-12mpg is not normal at all.
V8 Gelenvagen gets better mpgs and thats an all terrain vehicle lol.
anyway, it sounds like you are running rich air fuel mix. Air fuel sensor controls the mix ratio and it is getting information from oxygen sensor after the cat converter. If one of them or both are not working properly then you get messed up air / fuel ratio, in your case too much gas hence gas smell hence low mpg.
How many miles on your car? If you are over 100K on all original sensors i'd test and replace them if needed.
V8 Gelenvagen gets better mpgs and thats an all terrain vehicle lol.
anyway, it sounds like you are running rich air fuel mix. Air fuel sensor controls the mix ratio and it is getting information from oxygen sensor after the cat converter. If one of them or both are not working properly then you get messed up air / fuel ratio, in your case too much gas hence gas smell hence low mpg.
How many miles on your car? If you are over 100K on all original sensors i'd test and replace them if needed.
Hello,
Wonder if anyone can share your experience & knowledge for my issue -
My 2005 ES330's fuel cunsumption is about 12-14 mpg, which is really bad. I tried everything I could such as cleaning MAF sensor, replacing air filter, adding engine cleaner addtive. Unfortunately nothing is improved.
In addtion, I don't think gas tank leaks becasue I never smell gas when it parks in garage. However, I do smell gas from muffler pipe when the car is started.
Thanks in advance for your help!
Gary
Wonder if anyone can share your experience & knowledge for my issue -
My 2005 ES330's fuel cunsumption is about 12-14 mpg, which is really bad. I tried everything I could such as cleaning MAF sensor, replacing air filter, adding engine cleaner addtive. Unfortunately nothing is improved.
In addtion, I don't think gas tank leaks becasue I never smell gas when it parks in garage. However, I do smell gas from muffler pipe when the car is started.
Thanks in advance for your help!
Gary
Last edited by rlx101; 01-15-13 at 03:02 PM.