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Gas mileage

venram1venram1 Posts: 4
edited April 1 in Toyota
I've a 98 Corolla with 6700 miles on it. It still
doesn't give me the gas mileages posted on edmund's
site(28 in the city and 36 on the highway).
Recently I drove to a place 100 miles from Austin.
I was on cruise for the most part of the trip. I
got only about 31 mpg !!! I used to own a 96 Saturn
SL1 which used to give me more than 40mpg with
cruise on the highway.

So, is this something I need to check with the
dealer right away ? What could have possibly gone
wrong with the car ?

I already talked to a dealer over the phone once.
They mentioned that the 28/36 mileages were under
ideal conditions and the actuals may vary with
driving conditions etc. etc.

Thanks in advance for any feed back.



  • I am considering buying a 1999 F-250 Super Duty, supercab with an automatic transmission and four wheel drive. I have found reviews that give the mileage for the V-10 but I have not seen a review with the V-8. Does anybody know what kind of mileage the V-8 would deliver?
  • venram1,

    I bought a 99 corolla a month ago. At the first fill-up, I calculated 26.7mpg (mostly non-peak hours on Los Angeles freeways). I was told that a brand new car will not get it's optimum gas mileage. My 2nd, 3rd, and 4th fill-up were 35.5,
    35.2, and 31.5 mpg respectively.

    If you read the window sticker of the corolla, it will say in big prints 28/36 city/highway. But in the small print it says that actual mileage will vary with options, driving conditions, driver habit, and vehicle condition. It also says in small print that most cars in this class will achieve 23-33mpg in the city, and 30-42mpg on the highway.

    What do you usuall average on your corolla? 31mpg is not great, but it's also not all that bad. When you compare the mileage of your Saturn to your Corolla, are the conditions the same? For example: the load you're carrying, traffic, hills, etc.
  • Dear VEn,

    I'd say it's about as good as it's going to get,and 31 mpg is quite good. There's nothing wrong with the car. You might gain some improvement by checking tire pressure and inflating to maximum, using synthetic oil for faster warmups (less time on rich settings) and paying attention to driving habits. For instance, cruise control can often decrease mileage (LKF---little known fact). I'd say if you did all those three things, you could gain 1-2 mpg. Otherwise, be content, it's within specs.
  • Thanks for all your feedback. Jonyen98, the driving conditions of my Saturn are the same as the current Corolla I own. The fact that cruise control can often decrease mileage, really surprised me.
  • Gas mileage is a function of how far the accelerator is depressed. If you are in your top gear on the highway, using cruise control, and encounter a hill, the gas pedal goes way down. If you're in a stick shift, you can downshift, and perhaps lift up on the gas greatly. Also, if the freeway is hilly, using a downhill slope to speed the car up a little to prepare for the next uphill slope helps save gas too. Just a few instances where the cruise may not be as efficient as the driver.
  • Guitarzan:

    I always thought that cruise control gives you better mileage until I read the last few posts. From what you said, it sounds as if cruise control works OK if the highway is flat and not hilly at all.

    I also have another question regarding mileage on my 1999 LS400. I had a 1998 ES300 for about a year before trading it in for the 1999 LS400. For the one year that I owned the ES300, I got very good mileage with the car i.e. 25 MPG overall which is the same as or 1 mile off the sticker of the 1998 ES300.

    I have the LS400 for about 2 months now. So far, I only got about 21 MPG at best (about 3 or 4 miles off the sticker's of the car). I haven't changed my driving habit nor the route that I take to go to work. Any idea why this is the case ? Thanks.
  • I'd give it some time, first of all. The computer may need to learn your driving habits (just a guess, I don't know this for fact). Also, higher end cars typically have harder rings that take 10k miles or more to seat perfectly. Sorry, but I'm too lazy to check the weights and power capability of each of those cars. Are they similar, or is the LS much more powerful? Give it some time, in any case, and please report back.

    If I had such a car, I wouldn't even look at the gas figures. The "fun" part of it would erase any passing thoughts of economy.
  • Remember, dmattgam, you have two more mouths to feed now.
  • OK, Mr. Shiftright, I'll mark on my calendar two months from now to remind me. I'll report what I find after putting on a few thousand miles on my car.
  • Temperature can affect the mileage. So can atmospheric pressure. I've read somewhere that the higher the atmospheric pressure, the better the gaz mileage (it has to do with the density of the air). When the air is denser, the engine can 'breath in' a larger amount of air, providing a better combustion. I wonder if this is still valid for a moderm car that is all computerized? What I am sure about is that extremely low temperatures (-20) have an adverse affect of mileage. It would be fun to know under what conditions the mileage reported by a manufacturer is obtained. My guess is it's done with no head wind, higher atmospheric pressure and at temperature around 70-80 degrees.
  • Oh, yeah, the higher the altitude the lower the fuel mileage and the power....having a turbo helps this somewhat however.

    Manufacturer's use some kind of test cycle to determine mileage, and yes, it's under fairly ideal conditions.

    How you drive counts for a lot.. I have a standing bet with friends that i can get better gas mileage from their car then they radical tricks, shutting off the engine or coasting...just driving in your bare feet would help a little actually, but i don't recommend it on snowy days....tire pressure is very important too, and hardly anyone thinks of that...
  • KCRam@EdmundsKCRam@Edmunds Mt. Arlington NJPosts: 3,496

    THe mileage figures you see reported (from the EPA) are conducted in a lab that is set for "ideal" atmospheric conditions. In fact, it's not even a test for mileage. It's a fuel usage analysis based on the amount of emissions from the tailpipe. This is why you are always warned to use EPA figures for comparison only, and not to expect that mileage from the vehicle you drive. Because of public outcry that the numbers were unrealistic, the EPA even reduces the "public" figures.

    Here is the number calculation that is used - we'll use a 1999 "Edmund SE" sedan :)

    EPA test results by emissions analysis:
    26 mpg city
    38 mpg highway

    The EPA combined figure that tha manufacturer uses for their Corporate Average Fuel Economy (CAFE):
    2/3 city + 1/3 highway = 30 mpg

    The EPA "public" figures - what you see on the sticker:
    90% of city - 23 mpg
    78% of highway - 30 mpg

    KCRam - Pickups/Wagons/Vans+Minivans Moderator

  • KCRam@EdmundsKCRam@Edmunds Mt. Arlington NJPosts: 3,496
    oh, one thing to add: the city test is conducted at an average speed of 25 mph, the highway test is conducted at an average sped of 49 mph. Since the majority of us drive 65+ on the highway, you will probably never see the original highway number on an open road.

    In my example above, you can see that Edmunds can sell all the SE sedans they want, because the combined mpg figure is well above the CAFE requirement of 27.5 mpg. They can thus sell an equal number of cars that only get a combined value of 25 mpg. The truck CAFE is only 20.7 mpg - this is why you see so many V6 and V8 SUVs - they are balanced by 4 and 6 cylinder mini-trucks.

    KCRam - Pickups/Wagons/Vans+Minivans Moderator

  • shiposhipo Posts: 9,152
    In 1986, I was driving a 1985 Dodge Daytona Turbo from Chicago to Las Vegas. I stopped for the night in Council Bluffs, IA. The next morning, it was -15 degrees outside. I filled up in Omaha, NE, set the cruise control and drove non stop to Denver, CO! If I remember correctly, that was a distance of about 525 miles, on a single tank of gas. When I filled up in Denver, the car took less than 13 gallons of gas, it worked out to something like 42 mpg. I was stunned, prior to that tank, I had never gotten more that 400 miles on any single tank of gas.

    The next year I tried it again, it was ONLY about 10 degrees during the 1987 trip. I filled up in Omaha, set the cruise control and made it almost to Denver (I think that tank yielded about 510 miles). The only way I have been able to rationalize getting 25% better mileage on those two tanks was a combination of the following:
    1) Altitude, less wind resistance against the car (running at a steady 70mph).
    2) Turbo, while the air outside the engine was thinner, the turbo kept the air pressure inside "just right".
    3) Cold air, I have had two turbo cars, and they were always faster and got better mileage in cold weather. I assume that because of the cold(er) charge entering the intake manifold, the computer was able to keep the engine settings a little more aggressive than at warmer temperatures.

  • Some of what you say makes good sense, but not the altitude part if I'm reading you right...altitude should make the mileage worse. A good tailwind wouldn't hurt you either. It's hard to judge real mileage the way you were doing it, since you really need to have the car perfectly at the level (a slight tilt could throw you off two gallons easy) and you need to average it out over ten or twenty fill ups. But still it sounds like a good run for a car like that.
  • shiposhipo Posts: 9,152
    In a normally aspirated engine, altitude will certainly decrease fuel economy. In a car equipped with a turbo engine, moderate altitude (in the case of my Omaha to Denver runs, between 3000' and 5000') may in fact increase mileage.

    I am not a physicist, but I have studied the basic physics of a turbo charged engine. Maybe I have this all wrong, but based upon what I have learned about turbo charged engines, there is virtually no loss of power (just slightly more turbo lag) at moderate altitudes. At any given steady speed, the turbine will spin faster at moderate altitude vs. sea level keeping the intake manifold pressure virtually the same. In essence, down stream of the turbo, the engine will operate at virtually the same efficiency as at sea level. That being the case, with the engine producing power just as efficiently as always but with less dense air to push the car's body through, the vehicle should get better mileage.

    Did I miss something?

  • Well, he did say Denver, which is the Mile High City....but I was only relating my experience with my turbo car...the higher it went, the lower the fuel mileage, but I could agree that at a few thousand feet there wouldn't be much, if any difference...I'd buy that, but over 5,000 ft, I'd have to say that there's a loss of power even with a turbo, although much less than with an non-turbo car. I recall at 11,000 feet how many of the big engines really struggled.
  • shiposhipo Posts: 9,152

    I took both of my turbo cars up to around 12,000 (Loveland and Independence) and you are totally correct, lower mileage and power, BUT not as much as a normally aspirated car with a similar power rating.

    Both of my cars had boost gauges on the dash, it was very interesting to watch as the gauge would ever so slowly move it's way up the scale as the turbine would claw for every molecule of air it could find. Talk about "Turbo Lag" WOW, it seemed like it would take a full minute for the turbo to get wound up at very high altitude.

    Ahhhh, the good old days, now I commute in NYC traffic every day :-(.

  • markbuckmarkbuck Posts: 1,021
    Turbo engines normally have lower compression, so... if you are not in the boost (cruising at moderate throttle settings) your car could suffer even more at high altitudes. I live at 7,000 in Arizona and we have 20% less air pressure. When WFO, the turbo motor definately perform better, but at light throttle settings they seem worse. Also, peak horsepower and peak torque on naturally aspirated motors move to higher rpms at higher altitudes.
  • Yep, that's right...I always used to keep my engine wound up when at those extreme altitudes, to stay on boost as much as possible while Saab was a dog below 2500 rpms even at sea level.
This discussion has been closed.