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Sedans Honda Civic Honda Civic Real World MPG
2058 messages, Last post on Aug 26, 2009 at 6:19 PM
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Replying to: wai (Sep 12, 2008 9:59 am)  My worst mileage with my 08 EX 5spd was my first 2 tanks, and I got a little over 32 mpg on both. Then it started climbing. My overall average now at 7100 miles is 35.3 MPG and still climbing, and that's at about a 65/35 hwy/city mix. Considering the EPA combined estimate is 29 MPG, I don't think that is anything to sneeze at. Even better after coming from an '01 RAM 1500 that got 13 overall. My best tank has been 37.5 mpg, and that was mostly highway, under 65 for the most part, with no AC. I can duplicate 37 pretty consistently that way even with a 70/30 mix. All on good old RUL. I honestly don't think higher octane is going to be cost effective for you. |
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Replying to: mjsten (Sep 12, 2008 10:01 am) My brother has an '05 Accord 4 cylinder Automatic, and I remember him smiling about the freeway gas mileage early on, 40+ on some long leg of a journey. Don't know if that has remained constant over time, or if he ever uses higher Octane. I do know he uses full synthetic oil, FWIW. |
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I'm sure it's been said before but it bears saying, keep track of the type of fuel you are using. If it is an ethanol blend your milage may be between 10-20% LOWER than with a non-ethanol blend. Ethanol fuels dupe the computers in most cars into thinking they are running lean and cause them to make the fuel mixture richer i.e. pump more fuel thus lowering your milage. So if you are getting 29 MPG with an ethanol blend you could possibly increase your mileage to between 31.9 and 34.8 MPG just by switching. Just a thought.
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Replying to: sypher (Sep 15, 2008 5:04 am) Yes this is true but some states like New Hampshire have mandated 10% ethanol in all the gas sold here. So we don't have a choice. I know I could get better mpg if I was using straight gas. Sadly not an option for us here.
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Replying to: tiff_c (Sep 15, 2008 8:35 am) |
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Replying to: wai (Sep 12, 2008 5:16 am)
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Replying to: izmirian (Sep 15, 2008 5:29 pm) I think your mpg is very normal (more or less same as mine). You can experiment by using higher octane gas to see if there is any improvement.
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Replying to: wai (Sep 15, 2008 6:46 pm) Here are the conclusions, based on modern, computer controlled vehicles. There is no more energy in 92 than in 87. If a modern day car is designed to run on 87, there is no advantage to running 92. Higher octane simply means the fuel's ability to reduce the chances of engine "KNOCK" while under stress. Such as towing, heavy loads, red line operation, turbo or super charger applications, and such. Engine ignition "spark" is timed so that the fuel ignition begins when the piston has almost reached or slightly over ridden "TOP DEAD CENTER" of it's travel, and is ready for the "Explosion" that drives it down for it's power stroke. That explosion actually takes place over a period of time. The faster the piston is traveling, the earlier the spark can take place or "LEAD". If the chamber should over heat due to stressfull conditions, that extra heat can contribute to "pre-ignition", where the fuel is totally ignited too early. Under those stressfull conditions, if the engine should knock, the KNOCK SENSOR in the engine will retard the spark timing to compensate. Higher octane has additional additives to help prevent the knock and therefore help to keep the computer from having to retard the spark. Thereby probably helping to achieve slightly better mileage under those stressfull conditions. It gets a bit more complicated than that, but in layman terms that is the story. Bottom line. Under "Normal" conditions use the octane required by the manufacturer. There is no more energy in 92 than in 87. There are more "Anti-Knock" additives in the higher octane fuels. Under all "Normal" driving conditions, the engine computer will deal with the timing. One last thing. The temp gauge in the dash is reading water temperature. It will not indicate, except in rare conditions, the stress in the combustion chamber. So if you hear a "pinging" sound when the engine is under stressfull loads, a higher octane fuel may be in order, even though the temp gauge shows normal. Kip
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Replying to: kipk (Sep 16, 2008 5:21 am)
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the increased power in higher octane fuels comes from the "slower burn" of the high octane fuel. This sounds opposite of common sense, but a slower/ more even burn will give more power than a quick flash burn of a low octane. Higher compression engines are more prone to compression-ignition, that is, the fuel burns due to pressure instead of spark, and since compression burn (similar to a diesel) almost always happens too soon, pinging is the result. The engine with knock sensors will detect this and retard or delay the spark to reduce the pinging. Unfortunately retarding the ignition also reduces the power. So by using low octane fuel that is prone to pinging, the engine with knock sensors retards and power is lost. That's how lower octane fuel lowers power. In engines without knock sensors, the burn is just faster and that faster burn reduces power. And the knocking severely impacts engine life. The loss of power is noticeable in some cars more than others. My 97 Camry v6 (3.0L, 10.5:1 compression) was very much affected by octane. 93 would make it scream. My wife's 02 Highlander (same engine but with VVTI) has much less noticeable power loss on 87 vs 93. The VVTI in Toyota's case combined with newer ECU controls seems to avoid much of the discernable power lost by using 87 (91 is recommended in both the 02 Highlander and the 97 Camry). Honda's controls work in basically the same way. |
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