Serpent

Did my first calculation for my fuel mileage today and was a little disappointed. A week ago I bought an '11 Maxima SV w/premium, it's got 15,000 miles on it. Everything's stock (for now) besides the K&N panel air filter I slipped into the factory box this morning.

I filled up the tank to full, 91 octane, and used about 3/4 of the tank up with my driving today. Filled it back and and calculated my mileage to be 20.5 mpg.

The reason I was a little disappointed is that well over 90% of that driving was on a freeway doing 75-80 mpg on cruise control.

Was hoping to be a little closer to that 25 mark, but doesn't seem that I'm gonna get there.

Wondering what kinda mileage everyone else would've expected from their cars? Any suggestions for improving mpg (excluding driving style)? Synthetic oil, different intake, etc.?

lightonthehill

Cruise control will not give as good fuel efficiency as just carefully using your right foot on the accelerator. That is because cruise control does not anticipate any rise in the road, hence does not pick up any momentum to help maintain speed up the rise. So when the speed begins to drop, the CVT moves to a higher RPM and uses more gas in order to maintain the set speed.

Likewise, when going down a slight slope, cruise control will actually employ engine compression in order to prevent the car from exceeding the set speed. Using engine compression to decellerate on downhills not only raises the RPMs (using more fuel), but prevents the car from taking advantage of gravity on downslopes.

Measuring one tankful is rather meaningless, as has been explained here on the ORG several times each year (but it is too time consuming to scroll around looking for it). As I recall, there were dozens of reasons for this. Some that come quickly to mind are:
1 - Car may sit at slightly different angle side-to-side at different fillups, changing the point at which the pump says the tank is full to begin or end measurement.
2 - Car may sit at slightly different angle front-to-rear at different fillups, changing the point at which the pump says the tank is full to begin or end measurement.
3 - Different pumps have slightly different 'full' cutoffs, with some allowing more gas into the tank than others at trip's end.
4 - Trip might be into or with a slight breeze, which will result in different MPGs than driving with no wind.
5 - Be sure your tires are filled to at least 33 psi. Running with a psi below 30 will reduce your RPM.

Having said that, this car does not get as good fuel efficiency at 80 MPH as it does at 70, because the front nose of the car has a broad vertical surface in order to meet European pedestrian safety regulations. This gives more wind resistance at higher speeds than a sloped grille.

I have seen research that indicates using full synthetic oil can increase your MPG , but no more than a fraction of one MPG. You should get the same MPG on both 93 and 89 octane that you do on 91, but MPG usually drops with 87 octane, because 91 is the intended octane, and 87 is simply too far from 91 to run efficiently.

I would not be overly concerned until you have measured several tankfuls, and made a longer freeway trip in light traffic on a level road without using speed control. Most here are getting between 25 and 29 under such circumstances. A few get only 24, and a few get 30 or 31. But 26 to 28 would be the most common number posted here on the ORG.

And also keep in mind that this is a 3600 pound car with 290HP. When we slow down or stop for whatever reason, it takes a lot of energy to get this car back up to speed. That is why many here who do mostly conservative city driving (avoiding jackrabbit starts, etc) are getting only between 15 and 18 MPG.

We could ramble on here, but hopefully this will give you a few things to consider.

Ghozt

On a pure highway trip I'll see 29-31 but as soon as I mix in some city driving it'll drop to low 20's. I normally see 17-19 MPG day to day depending on how hard I'm driving

jkids

I drive mostly freeway, much of it stop and go; I average between 24-26

anish3232

When I use cruise I usually put the CVT in 6th gear manual mode and that will prevent the car from downshifting etc. I usually get 26-28mpg at 75-80mpg. Also the smooth roads in TN help.

Jodius Tha Warrior

I get 24 combined city and highway. I calculate after each fill up.

Give your max a few more months. The car needs to break in to achieve the factory rated mpg.

Serpent

Right on. Thanks for the reassurance and the always excellent info. Glad to hear I should expect a little improvement. Gotta keep fuel costs from getting too outrageous--I'm switching from an old civic that got 36ish mpg on 87 octane. I told my wife this car would never match that, but it should still do well. She was with me in the car when I was doing the math yesterday for milewge and she shot me a semi-evil glare when she saw the mileage and cost. Lol! Worth it though, I'm in love with this car!

Compusmurf

If you are comparing this car to a Civic in gas mileage, you are always going to be upset. Our leased 2012 Civic easily gets 43mpg hwy. I took it back and forth between Tampa and Orlando for a week and was getting 43+ consistently. Max, no way.

Of course, the Max is bigger, roomier, more powerful, a ton more comfortable, much more fun to drive, etc. Going to be a tradeoff somewhere.

Serpent

No doubt about that, and the sacrifice is SO worth it. This car is great. I just hope that the sacrifice isn't all the way down to 20.5 mpg highway driving. Lol.

I miss NOTHING about my '98 Civic. Glad to have moved up in the world!

Missouri-Max

I average around 24-25 with combined driving and 30 mpg on the highway with the cruise set at 70. I've got about a 50 mile commute for work with relatively flat terrain.

Amerikaner83

iTrader: (17)

turn off the A/C, that'll help too.

lightonthehill

But not as much as that tactic used to help.

Turning off the AC in the 1950s through the 1970s could mean around a 2 MPG improvement.

Turning off the AC in the 1980s and 1990s could mean around a 1 MPG improvement.

Turning off the ACC and keeping the windows closed in a car built these days will normally improve MPG by no more than a half of one MPG. AC compressors are far more efficient these days than they were in the olden days.

But if we turn off the AC on a car built these days and open the windows and get on the freeway, we actually LOWER our MPG a tad because the open windows disrupt the air flow moving around the car.

Amerikaner83

iTrader: (17)

Touche. Didn't realize that

Compusmurf

It was on Mythbusters too. I think they discovered the optimum speed to switch to AC was around 60MPH.

Of course, that was with THEIR test car.

lightonthehill

On mythbusters! I like mythbusters. There are thousands of myths that have become gospel for many folks. Mythbusters is one of the few places we can go to separate the wheat from the chaff.

Of course the improvements in vehicle air conditioners became very important for a reason we haven't mentioned here. When ACs were first put in cars in the 1950s, it was done with only one thing in mind - cooling. But over the years, it became clear that the air in cars closed up with the AC running became very clammy, and moisture tended to condense on the glass.

So dehumidifying became an additional chore of air conditioners.

By the 1970s or 1980s, engineers realized that dehumidifying was even more important in cold weather than it was in hot weather, so began making automobile AC units that could be used for dehumidification in winter without cooling the cabin.

At that point, it became obvious to engineers that automobile AC units were going to be needed year round - for cooling and dehumidification in summer, and just dehumidification in winter. So it became important to develop a compressor that had minimal effect on fuel efficiency.

That development has been successful, and now we have AC compressors that have minimal effect on fuel efficiency. Generally speaking, with exceptions such as winter days in the desert southwest, auto manufacturers and their engineers expect the AC in today's cars to always be on, with the thermostat set to the desired temperature. That is why all the vents and openings that we used to have in vehicles are long gone.

Jigesh Desai

hey Ghotz. got a question. i see that you have all 4 halos in. for the high beam did you get another hid or xenon conversion kit? if so what brand?

Ghozt

nah still running halogens. tbh i never use my high beams

BigFletch

Just don't stop at stop signs. That'll help. No cop, no stop.

Compusmurf

Of course, this is a joke because nobody would advocate illegal activities on this forum and risk a week's ban.

Amerikaner83

iTrader: (17)

BigFletch

Illegal? Nobody said anything about doing anything illegal. It's just frowned upon. Well, I guess until you get caught.

Sorry there is no standard sarcasim font.

Compusmurf

Since you're NEW around these parts, I'll cut you some slack, however, do read the rules and understand that discussions of road racing, running red lights and doing things on the highway that are against most state laws just aren't allowed here.

BigFletch

But having a thread showing illegal tint is ok?

Amerikaner83

iTrader: (17)

someone likes poking the bear, eh?

BigFletch

Depends. I understand not posting stuff that regards illegal acitivity, street racing, etc. But when they say nothing about mods that may be illegal per state, I see pics of illegal tint, lights, car height, etc. Not saying I wasn't in the wrong, which I do think it's dumb. Just trying to get an understanding for the rules that are in the gray area.

Compusmurf

Tint laws, height laws and stuff vary per state. Some states don't even have laws relating to that.

I do think stopping at a stop sign is universal in ALL states.

Celidor

I do a lot of city driving. And when driving conservatively I never get under 20mpg. In fact I usually get about 23-25 even when I'm not driving that conservatively. Continuously driving over 75 especially up any inclination is not going to get you great mileage. Letting cruise control work freely up and down hills will also lead to bad mpg numbers.

My2010FoUrDsC

I'm averaging 21-22 mpg, mostly half city/hwy. I normally drive on the freeway with CC set to 60-65 mph and the rpms is at 1800-2000. I find that my maxima is the most efficient when I'm on a flat surface, but considering the fact I live in Vegas, the freeways vary in elevation.

lightonthehill

That is very good city fuel efficiency. You are a more efficient city driver than I am. I tend to push too hard on the pedal.

One reason this car loses efficiency at higher speeds is the flat front, which meets strict European pedestrian impact requirements, but breaks the aerodynamic profile.

You are absolutely correct about the wastefulness of using cruise control in even slightly rolling terrain. We can be almost to the crest of a hill, doing fine at 1800 RPMS. But the vehicle speed slips barely below the set speed for the cruise control, and the system suddenly revs the RPMs to around 3k just to boost the speed 1 lousy MPH back to the speed we set.

Cruise control wastes even more fuel on downgrades, holding the speed back, and refusing to let the car use the benefit of gravity, which is available and free for the taking.

Zortster99

Just drove between Daytona Beach and Orlando. 70 miles at an average of 66.4 mph got me 29.1mpg. Of course I'll likely never see that again... I was an hour early for a meeting and decided to take my time and enjoy the day. My actual numbers for highway only were 27.9mpg @ 72 mpg.
MPG drops dramatically over 70 mpg / 2K RPM