Hey everyone! First time poster, long time lurker here.
Since gas has dropped more than $2.00 a gallon, I have noticed the gas mileage drop significantly on my car.
It is a 2003 Hyundai Elantra with 36k miles, I used to get about 25-27 mpg when I decided to start to drive more efficiently. After that I would see anywhere from 29-31 mpg. But then I noticed my mpg dropped to about 21-23 even with my good driving habits in effect.
I keep up with maintenance fairly well; plugs changed in January, air filter changed just recently, tire new and kept at proper pressure, although I haven’t done any of the not so simple to do stuff that isn’t easy to do such as cleaning the fuel injectors (which may contribute although I doubt they could be clogged enough to make such a big impact on a fairly low mileage car) , transmission flush (I don’t think that should impact my mileage at all, considering the low mileage again).
Some things I considered myself:
My choice of gas station, I usually go to the Pilot gas station, which is the closest to me, but I filled up at a Mobil a few times and there wasn’t a noticeable difference to the mpg.
Something is truly screwed up in my lovely :rolleyes: Korean car. But no trouble codes, no abnormal sounds, but I do notice not so good performance with acceleration, but thats not something I can isolate being a equipment problem or a side effect of my poor gas hypothothesis.
Whomever is adding the ethanol to the gasoline is putting a more than they should, not possible to go any further than a consideration, since I have no idea how to go about figuring out what the dealio with that is. (I have a few thoughts on gasohol :mad:, but I’ll leave that to another forum, probably the pit if I get bored)
I live in NY between NYC and Albany, a rural area if that could have a bearing on the potential answer I receive.
Don’t know if this applies to your area, but the timing is right. Many places require gasoline to have a certain amount of alcohol mixed in during the winter months. The usual start time is November 1. You get less power per unit volume with alcohol, so your mileage will drop about 10% or so when using it.
The reason for this is to reduce polution. Alcohol produces less polution than gas when burned in cars.
Also, most cars get worse mileage when the engine is cold. Depeding on where you live that could be a significant factor which changed over the last 30-60 days.
The topic leads me to a question that’s been on my mind lately. What IS the expected loss of MPG for gasoline with ethanol?
10% ethanol has lately become the norm around here. How much MPG should I expect to lose?
Also, I saw a station yesterday advertising “100% gasoline, no ethanol”. The price was 16 cents above the price for 10% ethanol. The question here would be; is it worth the extra cost?
Thanks.
Edit: 16 cents would be a 10.4% increase in price.
I remember being involved in a discussion on this board about this before, but I thought the Carnot cycle showed that you get better mileage when it’s cold, because there is a bigger temperature difference between the intake and exhaust. My car runs at about 212F when it’s about 90F out, and about 205F when it’s 30F out. But the gasoline is still burning at the same temperature in the cylinder, isn’t it?
I warm up the car for about 1 minute if I see frost around any cars, and continue to warm up my car every time I use it for the rest of the day. My car is fairly new, and I have heard that newer cars don’t need much more than a minute.
I have driven for a five years now(and this car for 2), and this is the first time that I have noticed such a significant loss of mpg in any car.
Gasahol may produce less pollution than just gasoline, but if it reduces efficiency by more than the percentage of ethanol in the gas, its actually causing a harmful effect to the pollution levels. If the addition of more ethanol to gas is the culprit for my sadness , then everyone is losing.
It is totally worth the difference in price, Ethanol is fairly corrosive, and unless you are driving a hybrid, (which is made to run on up to 9:1 ethanol-gasoline mixture) there is surely a performance and mpg difference. I wish I could find an ethanol-free gas station. I’d even have paid 10% more when gas was over $4 a gallon.
I don’t mean to shoot down every suggestion, but it is definitely not this. I recently was laid off, and money is tighter than it has ever been for me since I started driving.
I just did an mpg calculation today, and I got a whooping 20.4 mpg with this tank of gas. I went to a gas station in another county, so I’m going to see if its the location thats the problem.
I have this lingering thought in the back of my mind that gas became as cheap as it did because of quality reasons more than demand reasons (It makes business sense to me, if you can cut costs by 50% to make a product seem more appealing, and people buy >50% more of said product, business wins and customers think they win), but I know nothing of the supply and demand of oil. Its this thought that had me ask my question.
My local newspaper had an article about this about a month or two ago. Most of the local gas sellers were switched to the 10% ethanol (This is south-central PA).
The whole article was about how people were getting about 10% less fuel efficiency once their neighborhood gas stations switched to 10% ethanol. It was a local reporter, so I can’t cite a big fact, but man-on-the-street interviews were returning what you suggested, the MPG dropped about 10% with the ethanol additive.
This sparked local gas sellers to advertise IF they were selling non-ethanol gas, which was usually .10-.20 more per gallon. It’s kinda a wash overall from what I’ve seen, pay .20 less per gallon and give up 5-10% MPG, or pay .20 more/gallon and keep getting what you’ve been getting.
This is an overall synopsis of the article, older cars probably do fair much better (maitenance + MPG) on pure gasoline rather than ethonal.
The issue is that while the engine is cold, the fuel injuection system sprays a lot more fuel into each intake stroke to offset the poor vaporization. So while the molecules of fuel which burn may produce more power in a pure Carnot analysis, a lot of other fuel is being dumped out the tailpipe unburned. And that unburned fuel more than offsets the small Carnot gain you mention.
Natuarally, as EFC has gotten better and the drive for both low emissions & high mileage have gotten stronger, the warmup enrichment cycle is getting smaller in size & shorter in time. If you live where winter mornings = 50F, the effect is negligible unless you’re only driving a mile or so. If you live where winter mornings are -20F, the effect is measurable unless you’re driving (WAG) 20+ miles.
The proper term for these seasonal additives is oxygenates. Wiki article
According to the EPA (take the link to chapter 3 PDF!), You will lose about 2-3% in your fuel mileage.
So where is the other 7% going?
Cold start and warm up is one huge consumer of extra gasoline. When it is cold the fuel system literally dumps gas in the engine in order to get it to start and run until it is warm. If by the way, your thermostat is bad, and opening too soon (not maintaining the proper engine temp), you gas mileage can take a substantial hit as the EFI system may never come out of cold start/warm up mode, and continue to inject extra gasoline.
Warming your car up before driving is another. Modern cars do not need to be warmed up before driving. Sitting in your driveway idling will kill gas mileage like nobodies business. Your car will warm up faster if you get in and drive it. Your gas mileage will improve also.
That makes sense, thanks! And even though the cylinder walls will be at roughly the same temperature, the fuel will be meeting the cold intake air, so it will have a lower vaporization pressure. If it was advantageous to warm the fuel first, we’d probably see it in cars. But, since we don’t, it’s probably not worth the energy to heat the fuel. I’ll remember that explanation next time, thanks again.
Does this correspond to the time of the noticed MPG drop? Did you have a commute?
If you used to use gas for commuting plus errands and now you only use it for errands, you might just be seeing the MPG that you have always been getting for the typical errand trips you take. (Many shorter trips with a colder engine, perhaps more stop-and-go/idling around town and in parking lots, less highway, etc.) This would be quite noticable if your commute was, say, a 10 to 30 minute straight-shot 55-70 mph affair.
Well, you see the OP is decribing a 25% or so reduction in MPG (and t’s supposed to bte less than a %5 reduction). And, “the man is the street” usually couldn’t figure his milage if you gave him a half an hour and a calculator.
But Pasta may have a key- if MatthewStabile is now driving short around time trips instead of longer mostly freeway miles, that could account for a reduction of 25%.
I haven’t had the car checked out, for monetary reasons. I can just see the dollar signs cha-chinging in the eyes of any mechanic that I would express my problem to. I’m open to the idea that there is something wrong with my car, but unless I could get more specific on what is wrong, it is cost prohibitive
I did the spark plugs back in Jan, along with the air filter, I didn’t change the spark plug wires because they didn’t look bad. I had the front oxygen sensor replaced last year because it malfunctioned, and I probably should flush out the coolant, but it didn’t look absolutely horrid when I last checked it.
I’m not exactly sure what else would be part of a tune up, my car knowledge is extremely limited.
Something wrong with the thermostat could be possible. What could the possible signs of this be? My temperature gauge doesn’t show anything abnormal, no movement until I have been driving for about a minute, then after about 4 more minutes, it reaches normal spot, just a little short of the midpoint on the gauge. No rotten egg smell(I think thats a sign for unburned gasoline, pardon my ignorance if it isn’t).
You are duelly noted about warming up cars. It might have even been you that I remembered reading about car warm ups(This would be years ago if this is true), I just probably misremembered it.
No commute, I live 5 minutes from my ex-job. All of my driving is on 45-55 mph rural roads. I go near a city on my errands, but not more often than I ever have.
, then everyone is losing.