This is my first post on this forum. I've already learned I need to due a transmission fluid change asap and before coming to this forum I've heard horror stories about the CVT transmissions around 80k miles.
My wife always drives our 2012 Nissan Quest S but I noticed that the engine is louder than normal when stepping on the accelerator. Also noticed the fuel economy which was always at 19.1 average is down to 18.8. Any ideas? I currently have 58K miles and haven't done any maintenance except air filter , oil changes, brakes and tires. Bought it used in 2014 with 19k miles on it.
Thanks in advance for any help
Engine revs louder, gas mileage down slightly
Re: Engine revs louder, gas mileage down slightly
Not sure where you live, but cold weather will effect the fuel economy and warm-up process, which may be where the noise is coming from. Dropping from 19.1 to 18.8 is nothing. Pretty sure we get less than that with our 2016 Quest in the cold weather. I think the only difference between your 2012 and my 2016 is a slightly different CVT trans.
Re: Engine revs louder, gas mileage down slightly
I thought maybe changing the air filter would help but it didn't. Now I have a new theory to explain the lower mpg (assuming it's not just general aging of the engine). A few months back the wife let go of the driver side door and a gust of wind flung it so hard it damaged the hinge. Now I hear subtle wind noise coming from the top back corner of the driver side door (easier to hear at highway speeds). Could the air drag be enough to drop the mpg? Also the louder engine noise may be unrelated because a braided metal sleeve thingy came off an exhaust pipe and maybe that helped muffle some noise ? Sorry for my lack of technical terms.
Re: Engine revs louder, gas mileage down slightly
mac , the aerodynamic change , air noise ,getting drag - you probably got something there. I've brought up to many , a theory , many completely dismiss : how when I get a perfectly smooth & shiny wax ( first noticed on a Express van) Gas mileage afterwards improves , for real - YMMV ! 
. Ya know when that wipe rag flys across the hood ,slippery slick surface = air drag makes a SUBSTANTIAL difference. You look at how a tennis ball has the FUZZ , limits it's top speed (intentional) , well a real dirty car , you can feel roughness all along the surface , race car teams obviously exploit the last MPH in ALL ways possible. GT 2/25/2018
. Ya know when that wipe rag flys across the hood ,slippery slick surface = air drag makes a SUBSTANTIAL difference. You look at how a tennis ball has the FUZZ , limits it's top speed (intentional) , well a real dirty car , you can feel roughness all along the surface , race car teams obviously exploit the last MPH in ALL ways possible. GT 2/25/2018Re: Engine revs louder, gas mileage down slightly
It's not that much at all, I used to wax 200 mph race cars and the difference may be there but so slight it's in the variable. And the idea completely ignores the boundary layer which is proven fact.
OP is micromanaging the mileage thing in his head, the difference in ethanol if used where he fuels up could easily make that difference day to day. And thinking before all that the number always stayed at 19.1? Ridiculous. Real world mileage ALWAYS changes, there is no way to drive a car the same way twice as the daily conditions change and even minute to minute.
The door would have to stick out in the air like 1/4" more before any measurable difference at all. There is constant turbulence in and around the door seals at all times even new, it's just that leaking that into car can make more noise without any more drag whatsoever. Crack your window open 1/4" and measure the mileage decrease, if you find it you are imagining things, it buries in the variables. Yet the noise increases greatly, it was always there, just not let in.
in my world 18.8 and 19.1 are the same number when it comes to mileage, there is easily that much variable day to day.
OP is micromanaging the mileage thing in his head, the difference in ethanol if used where he fuels up could easily make that difference day to day. And thinking before all that the number always stayed at 19.1? Ridiculous. Real world mileage ALWAYS changes, there is no way to drive a car the same way twice as the daily conditions change and even minute to minute.
The door would have to stick out in the air like 1/4" more before any measurable difference at all. There is constant turbulence in and around the door seals at all times even new, it's just that leaking that into car can make more noise without any more drag whatsoever. Crack your window open 1/4" and measure the mileage decrease, if you find it you are imagining things, it buries in the variables. Yet the noise increases greatly, it was always there, just not let in.
in my world 18.8 and 19.1 are the same number when it comes to mileage, there is easily that much variable day to day.
Re: Engine revs louder, gas mileage down slightly
It's my wife's car and she informed me that she has seen the average mileage display 19.2 or 19.3 on long road trips. It also dawned on me that I got new brakes and tires shortly before the door hinge incident. They are good year and different from what the car came with