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Hybrid Vehicles Nissan Altima Hybrid Nissan Altima Hybrid
321 messages, Last post on Nov 19, 2009 at 9:31 PM
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Replying to: townboy325 (Jan 02, 2008 5:36 am)
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Replying to: townboy325 (Jan 03, 2008 2:59 am) We JUST hit 10K on our car on a trip, returning from friends' house in Sacramento, California. My wife, who is a much more gentle driver than I am, probably averaged about 75. We got 40 MPG according to the car's computer. Impressive for freeway driving, to say the least. We've also noted that the machinery is getting looser and looser (more broken in). When we first got the car, it wouldn't stay in EV mode much above 30. Now, it's common to see it top 40 for short distances before it switches to ICE. With crude oil hitting 100, we're very pleased.....
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Replying to: hiwayman (Jan 03, 2008 8:43 am)
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| I am liking this car more and more each day and appreciating the combined engineering of Nissan and Toyota. What a combination. | |
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Replying to: hiwayman (Jan 03, 2008 8:43 am) |
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Replying to: mazda6dude (Jan 03, 2008 11:23 am) We were pretty surprised by the 40 MPG figure, too. We'd never seen the mileage that high. Generally, our combined mileage (city/hiway) runs in the mid 30's. The only thing we can figure about the 40 MPG is that we had a tail wind. As you know, the long stretches of 80 headed back west from the Sacramento area can be pretty windy. We also drove about 30 miles on very slow roads (Hwy 49, from Grass Valley to I-80), so that probably pushed the mileage considerably. Additionally, where I'll drive pushing 80 MPH, my wife is more of a 65-70 driver (she was driving), so that may have contributed to it as well. We see a significant difference in gas mileage when we change the cruising speed from 80-ish to 70-ish. Since we're not seeing that mileage since that trip, there must've been some external factor. And oh yeah, in answer to your question about where I live, it's actually in Marin County, north of San Francisco.....where herds of Priuses roam, free range....glad we have a NAH! I've heard that the computer isn't that accurate. That's cool, because I generally look for trends in gas mileage that would indicate better driving habits or some system problem, and don't trust it completely. However, the thing that should be considered is that there is significant chance for human error when filling a tank with gas. One gas pump may let you fill the tank much fuller before clicking off, than another. If the car is actually getting the same gas mileage from tank to tank, and you don't fill the tank to the same level each time, your calculations of mileage, based upon what you pumped v. miles you drove will differ, even though, in reality, your car is getting exactly the same mileage. A difference of a MPG or two is well within the margin of error for filling a gas tank differently. That is something to think about. When car mags and other organizations do mileage tests, they always try to fill the tank the same way each time, and sometimes even use external, carefully-calibrated tanks, when they do the checking. The car, on the other hand, calculates gas mileage by monitoring the fuel injection system. It knows very precisely how much fuel is being used, since it needs to know that to manage emmissions correctly. In the new closed-loop emission systems, the sniffers in the exhaust system tell the car's computers how to adjust the fuel injection at a very precise level, to assure best performance of the emissions system. Having to do that makes the car pretty precise in its knowledge of fuel usage. If you make the assumption that the odometer is accurate, I'd bet that the car's calculation of gas mileage is probably the accurate number, not the hand-calculated number we humans make...catch my drift? As far as why your gas mileage is so low, it's hard to say. It is unlikely that there's something wrong with the car, since one of those dozens of little lights on the instrument panel would most likely glare at you if there was. It probably has to do with a few things. Thing 1. Your driving style. If you like to squirt through traffic, and accelerate crisply away from stops, and drive fast, that will definitely lower your gas mileage. From the sounds of the cars you've owned, I'd bet ya coffee that's the way you like to drive. It's fun, but it uses gas. Thing 2. The Toyota-based hybrids like ours get their best mileage in stop-n-go traffic, where they can stay in EV mode. If you're not in knotty traffic, much, you won't get the high numbers. This was a lesson we had to learn as we got used to our car. We were disappointed at first, too, until we realized that in our area we do very little "city" driving, and as a result don't see the high-end numbers. The other thing is, when I drive the NAH, I get mileage similar to yours, because I like to drive aggressively too. When my wife drives the car, she probably squeaks out an additional 5MPG, because she's a much more gentle driver, and actually enjoys trying to keep the thing in EV mode. As a matter of fact, I hear about it all the time from her, since she checks the mileage computer frequently. I did get even, though. A few weeks ago, after hearing once again about how low my mileage was, I found a nice long hill. I reset the fuel mileage, and then rolled down that hill, hitting over 50 MPG at one point. I drove like I had egg shells between my foot and the accellerator for the mile or two headed home, and when I pulled into the driveway, my mileage, according to the computer, was in the mid-40's. I left the mileage indicator up, so my wife would see it next time she drove the car. OK. OK. So I cheated. But it WAS funny. She was oddly quiet about fuel mileage for a few days after that (probably trying to match my cheated numbers). When she finally mentioned it, I couldn't stop laughing, so she knew she'd been had.... Hmmmm...wonder if that's the way the EPA works it? 
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Replying to: hiwayman (Jan 08, 2008 2:31 pm) Your explanation makes sense. As for my driving habit, I drive very smoothly and this is where I don't understand my MPG. I got 31MPG on my last tank, but I filled up again yesterday and I got 39MPG. That is a big change and my driving habit is the same. It was the first time a I got 31MPG and the second time I got 39MPG. I keep a track everytime I fill up. Maybe you can answer this question: when I fill up gas, do the gas tank really become full when the first click happens or can the gas tank take more gas? I have got varying answers, but I still don't know what is the truth. I usually fill up gas and then go one more click after the first click. On my last car, which was a Mazda 6, my MPG's didn't change much. Always stayed around 28-29 range. Yet, with my NAH, its all over the charts. I see no consistency. I do a lot of freeway driving. I am more like 90% Freeway and 10% city. On my trip computer, I keep it on the "Range" reading and the funny part is, the range increases more on the freeway, while in city driving it decreases. Lastly, I have started to keep my NAH going smooth at one speed in the city instead trying to keep it in EV mode because EV mode goes in and out. Do you think the MPG will be better this way or just accelerate and then keep it in EV and then accelerate again to keep it in EV mode and keep doing this over and over again? Wouldn't having a constant speed regardless of EV Mode, help your MPG? Driving a hybrid is very interesting and there is always something to learn. I appreciate your input.
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Replying to: mazda6dude (Jan 08, 2008 3:13 pm) Mileage differences go back to that discussion we had about how you fill your tank. The nozzles on gas pumps are pretty variable, even within the same gas station. Some will click off too soon and some will actually click off too late, even going as far as to spew fuel on the ground (most drivers have probably experienced that). That can account for up to a gallon, even two, difference in the fill. The principle of a gas hose is that it clicks off when backpressure gets high enough. High backpressure indicates fuel touching the end of the hose (full tank). The problem, especially in California, is that there is a gas vapor recycling system (that's that accordion-like thing on the hose). If it is plugged, or if the hose slips out of the car even slightly, the pump will click off. Additionally, the sensors that sense the backpressure don't have any real standard, and can click off the fuel flow in a wide range of variables. You may THINK you have a full tank, but you may not actually have that. I myself was on a trip a few weeks ago. Was filling up at some little gas station down in mid-state. That pump would NOT fill my tank past 3/4 full for some reason. Something wrong with the sensor on the hose. If I'd calculated my gas mileage there, I would have had some pretty strange numbers. So, here's a scenario that would affect gas mileage..There's all kinds, but this one would probably be common. You fill up your tank. The pump clicks off too soon. You get 10 gallons into the tank, then look at your trip meter, which shows you've gone 400 miles. You think your gas mileage is 40 MPG. OK. Now you drive for a while. You fill up again after 400 miles. This time the pump works correctly. You pump 12 gallons of gas (10 gallons, plus the two you missed in the last fill-up due to the early shut off) You do your calculations. They show you've gotten 33.3 MPG. The reality is that your car is getting about the same gas mileage, but because of variability in the fill ups, you're showing a significant difference in mileage. How do you fix that? Well, there's not really any way to fix it, other than to be really sure your tank is actually full (several clicks, and jockeying the hose in the filler pipe a couple of times will reduce the problem I just discussed, but not completely). By the way, on my NAH, I've noticed that the fuel gauge is pretty accurate. When it's showing 1/2 tank, I pump 10 gallons (assuming the pump is working right). That being the case, the range (which is, as you know, the car's calculation of how much range you've got left, based upon your average mileage, and the amount of fuel you have left) should be pretty accurate. Now an interesting thing about your story is that you say your mileage range shown by the car's computer decreases in the city. This would indicate that your city driving doesn't stay in EV much. EV is where you'll get the big numbers. A car using it's ICE (Internal Combustion Engine) gets the crappiest mileage in the city, because acceleration and stop/go driving is what hammers gas mileage. Every time your ICE kicks in, in city driving, your range will decrease, since your hybrid is behaving more like a conventional car at that point. It's tough to stay in EV mode, especially with someone crowding you from behind, but staying in EV mode is necessary to get those long ranges, and "upsidedown" mileage numbers that hybrid cars are known for (big city mileage, not as good hiway milage). One final comment (at least for now..haha). If you suspect that something isn't working right in your car, there ARE situations where something might be misbehaving, and your dashboard trouble lights won't illuminate. If you think you've got a problem, take your car in and get the Nissan folks to put it on the scanalyzer. If something is wrong, your car's computer will let them know, when it talks to the scanalyzer.....
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Replying to: hiwayman (Jan 09, 2008 12:00 pm) Thanks for the explanation. I just might take it in for a scanalyzer and find out what is going on. One time I filled up the gas and it was full, but the fuel gauge didn't show that until a few minuted into driving. I thought something was wrong with the fuel gauge. Also, I figure out my MPG by doing my own calculations. You are totally right about EV mode. First, its hard to stay in EV mode and second, people crowd up behind you. I try to stay in EV mode whens its possible, but most of the time, I keep a constant smooth speed. I have already had one problem with my NAH and that was the car was pulling to the right. The dealer fixed the problem, but no after I filed a claim with BBB and went through tremendous hassle. Actually, I have never spent so much time on any of my cars trying to fix a problem until I has this problem with my NAH (pulling to the right.) I still believe the problem is not fixed because the shop foreman couldn't guarantee the problem was not going to comeback. |
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Replying to: mazda6dude (Jan 08, 2008 3:13 pm) I think it all depends on the pump. There were some places where I could put in an extra gallon after the first click. and then there were other places where gas spews out right after the 1st click. I don't think your long-term gas mileage is really affected by this as it all gets weighed out in the end |
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