Last post on Oct 23, 2013 at 12:16 PM
You are in the Nissan Altima
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Nissan Altima, Fuel Efficiency (MPG), Sedan
#287 of 306 Followup on low MPG: pollution&catalytic converters
Sep 04, 2012 (11:37 am)
Summary of what I learned from a Nissan "expert driver":
Making short trips is bad for your gas mileage.
Apparently a catalytic converter needs to be hot to do its job properly, and your car would produce drastically more air pollution if you drove around normally until it warmed up. To meet pollution standards, when you first start your Altima (and presumably most modern gas engines?) the car invests a surprising amount of energy idling fast to quickly heat the catalytic converter. So for the first couple of minutes you are in the car it is in a gas-expensive but pollution-reducing mode, and if you only drive for two minutes every time then you will get abysmal gas mileage. If you generally take five or ten minute trips, your mileage will still be noticeably worse than if you drove the same distance in one trip, because you burn extra gasoline each time you start driving.
I want to point out that polite persistence can be very helpful in situations like this. I spent a lot of time talking to my dealer, and got to meet "the expert from Nissan" who explained that my car is perfectly capable of getting 35+ mpg driving on an empty freeway etc. He insisted that he couldn't tell me why I would consistently get half of that without being there to watch my driving habits, and waited for me to accept that I must be doing something strange and walk away.
I spent an extra 20 minutes patiently restating that I needed to figure out what the problem was because it was costing me a lot of money, so would he please list the things that I might be doing wrong. He reluctantly tried thinking of a few, and was impatient when I told him that each one didn't happen to apply in my case. In frustration he eventually said "the only person I've ever heard of getting such low mpg is my wife, but she only takes the car for short trips of a mile or two."
How to take advantage of this information is a whole separate problem, since I live in L.A. and am therefore legally forbidden to walk anywhere that a car could take me.
#288 of 306 Re: Followup on low MPG: pollution&catalytic converters [poormpginla]
Sep 04, 2012 (11:48 am)
Since you have spent so much time working with the dealer to resolve your problem one would think the dealer would have insisted that the "expert" from Nissan drive your car to see if a so called expert could get a decent mpg number. It wouldn't have taken more longer than your conversation did. I did notice on the rental Altima I recently drove that city driving really drove the MPG down.
One thing I can't understand in all this is that all I hear from Nissan is that the CVT is supposed to be so much better for MPG than conventional transmissions. But when you compare the other top midsize cars to the Altima(ie Sonata, Camry, Accord, etc) they are comparable in HP, weight and MPG. You would think if the CVT was that big of factor the Altima would kill the rest but that's not the case.
I understand the new 2013 Altima has jumped in MPG but the older model Altimas have had the CVT for years and have never been ahead or even equal to some of the other midsizers with conventional transmissions. Just wondering why if the CVT is all that wonderful.
#289 of 306 2013 3.5 SL mpg
Sep 04, 2012 (6:55 pm)
New car. MPG so far as follows:
24.4 (mostly town/some highway)
20.0 (all city, heavy stop/go, 3 mile or less trips, two weeks)
40.0 (yes, 40 - all highway, cruise set at posted limits of 65, 75)
35.0 (75/25 highway/city, 560 mile trip)
That's right. These were calculated using fillups. And I mean filled to the TOP. All are with the climate control set on auto, usually A/C running.
Car has 1900 miles to date and the mpg avg on the screen is 27.2.
Engine RPM's at speed are very, very low - 1400 to 1750 depending on speed, holding cruise. Around town, with a light foot, you can keep it well under 2000 all the time.
The car responds well to careful driving, paying attention to RPM's.
Of course if you floor it, all bets are off, and the 3.5 certainly delivers with acceleration (I've read that it does the quarter mile in 14.3 and I have no reason to doubt it) that's impressive for a car at this price point.
So, to date, I couldn't be happier with the MPG. We'll see how winter affects it with heavy snow and city driving.
Also, the seats and stereo are outstanding. This is quite the car even for sticker price.
#290 of 306 Re: 2013 3.5 SL mpg [mtpete]
Sep 07, 2012 (9:10 am)
Do U use Regualr unleaded or premium unleaded?
#291 of 306 Re: Followup on low MPG: pollution&catalytic converters [m6user]
Sep 11, 2012 (11:36 am)
Yes, the expert did drive my car before our conversation. He got great mileage: presumably this is part of why he was impatient with me, since in his mind he had already spent an hour proving that there was nothing to complain about.
Of course, an expert driver paying attention only to his mileage, filling up the tank literally next to the onramp and and then the offramp so that he drove 99% on a freeway, was always going to get great mileage. He proudly showed me his receipts, proving he got 35mpg in my car. But I have effectively tried the same experiment, driving a couple of hours each way almost entirely on freeways . I got 32 mpg. (My OBC said I had been getting 35 mpg if you trust that more than my own fill-drive-refill-divide calculation.) Yes, my car can do it; no, I'm not an inherently gas-wasteful driver.
So why *have* I been getting between 14 mpg and 19 mpg on almost every tank of gas since I got the car (new)? The one surprising answer I have been given is that really short trips give really terrible mpg. So a (very) short commute does save me money on gas, but not quite as much as I would have thought.
It had never occurred to me that my car would burn significantly more gas in the first mile or two, revving fast in a fuel-inefficient effort to warm the catalytic converter quickly. It may not even be true. But I figured it was worth sharing the idea here.
#292 of 306 Re: Followup on low MPG: pollution&catalytic converters [poormpginla]
Sep 11, 2012 (2:28 pm)
If the kind of driving you do most of the time is very, very short trips of less than 3-4 miles or running a bunch of errands where you start and stop the engine several times in a relatively short trip, then you are going to get the worst possible mileage. And that would be with any car but the newer cars it may even be worse than the old ones. The EPA city mpg test is not nearly as severe as I described above so you should expect significantly less MPG thant even the EPA city rating for your vehilce. Remember they try to simulate a lot of differnent kinds of city driving to come up with their city rating. Even the city rating will have a range associated with it and it sounds like your type of trips may be on the lower end or even lower than than the lower end of their city MPG range.
Comparing a car that is ten years old or older may not be a great comparison as these new cars are tuned a lot differently to get that high MPG in normal situations. If your situation is well off of normal than you may even get worse MPG with your newer car than with an older one if that makes any sense to you.
#293 of 306 Re: 2013 3.5 SL mpg [ahossa1]
Sep 16, 2012 (12:43 pm)
So far straight premium.
Just had another almost 600 mile trip - came in at 32 mpg, mixed driving, over steep mountain passes.
Sep 22, 2012 (10:40 am)
I have my altima for 2 weeks now and the guage shows me 28.4 mpg (may be bcs all of my driving has been in city and yesterday was stuck in traffic for 45 min due to acc) how to reset those numbers? I've yet to take a long trip on freeway and than see how the mpg numbers behave
One of my relative adivsed me to use premium every 4 - 5 fill ups that will extend engine life. Is that true? Can I do that? Has anyone any exp of how it affects engine?
#295 of 306 Re: bad MPG [jimfish1]
Sep 22, 2012 (8:10 pm)
It is very sad that my 2011 2.5 Nissan Altima Coupe can't get better than 27 MPG on the highway. I do like quiet and comfort of my Coupe. I traded my 09 Civic hybrid in on this and I got 45 to 50 MPG all the time. The stated 32 MPG on the EPA window sticker was the deciding factor. Nissan grossly over estimated ergo... it was a lie. I don't know anybody that gets my 27 MPG let alone the 32 MPG Nissan advertised. I could have got the 3.5 or better yet a Mustang 5.0. I won't be buying a nissan again.
#296 of 306 Re: bad MPG [bartosis]
Sep 26, 2012 (3:29 am)
I have a 3.5 liter Nissan Maxima. Bigger engine than your 2.5 and the maxima is heavier than the Altima but I easily get better highway mileage than what you are getting. You should be getting much better MPG. It should be easy to get the EPA's numbers or better. Most people I know get much better MPG than what you're experiencing and most get better than the EPA.