gas mileage sudden drop 10%
09-17-14, 06:32 PM
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gas mileage sudden drop 10%
so my 2013 E300H has been getting the 40+ MPG for the first 30000 miles (over 1.5 years ) so far.
however this past month (or 3 tanks of gas) it has drooped from average of 40.5 to 41 mpg to 36.5 to 37 mpg.
I always go to the same gas station (sam's club) so the grade of gas did not change over the year.
the only thing i can think of is that it has been horribly hot this last month and I ran the A/C more often than not. but it has been 2 summers since i purchased this car and i certainly don't remember a 10% drop in MPG even in the hottest day last summer.
only thing i can think of is that i started using my own mechanic for oil change instead of going to Lexus dealership (they changed oil at 5k and 15k) that's it. but that was 10K miles ago. and this drop just happens in the last 1000 miles or so.
anyone have ideas , advice or theory?
however this past month (or 3 tanks of gas) it has drooped from average of 40.5 to 41 mpg to 36.5 to 37 mpg.
I always go to the same gas station (sam's club) so the grade of gas did not change over the year.
the only thing i can think of is that it has been horribly hot this last month and I ran the A/C more often than not. but it has been 2 summers since i purchased this car and i certainly don't remember a 10% drop in MPG even in the hottest day last summer.
only thing i can think of is that i started using my own mechanic for oil change instead of going to Lexus dealership (they changed oil at 5k and 15k) that's it. but that was 10K miles ago. and this drop just happens in the last 1000 miles or so.
anyone have ideas , advice or theory?
Last edited by nakago1; 09-17-14 at 07:06 PM.
09-17-14, 08:03 PM
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I can only say that I had a Prius and my MPG always dropped about 10% when using the A/C. The A/C on either car doesn't draw power from the gas engine like a normal car does, it's all electric, but it does draw heavily from the batteries which makes the gas engine charge the batteries more frequently. So indirectly the A/C does affect the engine usage and therefore MPG.
09-18-14, 05:06 AM
#3
I'll second the air-conditioner theory. I live in south Florida, so I use the AC almost year round. I get about a 10 percent bonus (increased mpg) during the months each year when my AC doesn't run constantly.
It could have something to do with where you have been driving; how much traffic is on those roads; road construction on your routes; if you have been in a hurry; and such. Even one hurried trip can hit your mpgs for the whole tank.
It is possible there is something going on in your engine. But those things would have other symptoms, and most would make your check-engine light turn on. Absent those symptoms, that seems unlikely.
In the end, it is only 4 mpg (from 41 to 37), so your fuel bill is higher by about $3 per week. If that seems like a lot, ask someone who drives a full-sized pickup truck or SUV how much they pay for fuel.
It could have something to do with where you have been driving; how much traffic is on those roads; road construction on your routes; if you have been in a hurry; and such. Even one hurried trip can hit your mpgs for the whole tank.
It is possible there is something going on in your engine. But those things would have other symptoms, and most would make your check-engine light turn on. Absent those symptoms, that seems unlikely.
In the end, it is only 4 mpg (from 41 to 37), so your fuel bill is higher by about $3 per week. If that seems like a lot, ask someone who drives a full-sized pickup truck or SUV how much they pay for fuel.
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