06 M35 Gas Mileage

[jda1015]

Hey Everyone - I know a million different people have posted regarding fuel mileage, but I was just curious as to what everyone thought about mine. I bought the car back at the beginning of October and have been experiencing pretty terrible mpg. When I look at the info screen and fuel economy I'm averaging around 13.6 - 14.0 per tank. So my M has 25K miles and is due for an oil and filter change, so I know that will help. Also, about 90% of my driving is all in city stop and go in the los angeles area, but I would still think that with proper tire inflation and all the rest of the typical stuff I would at least get 15 - 16 in city right? I'm not driving particularly hard... Has anyone noticed a difference using 91 octane as proposed to 87? I've tried both, but seems about the same to me. Also, I still have the stock sport tires on the car and am wondering how much pressure everyone keeps them at? Sorry for the rambling. I am greatly looking forward to your answers! Thanks for taking the time in advance. I'm going to try and take some pics and get them up here soon.

[NightWatch]

If most of your mileage is stop and go city traffic, that might be about right. My commute is 28 miles each way at an average of 20mph (gotta love Atlanta Traffic). I consistently get 20mpg using 93 octane. Based on the cautions in the manual, I don't think I'd use anything less than 91. Oddly enough on a recent trip to Sarasota FL my highway mileage wasn't much better, I averaged 22mpg at 70-75mph, cruise control set, no traffic. I was a bit disappointed. On the way back I tried driving for 200 miles at 60mph and my mileage shot up to 26mpg. I think this car is a lot of weight for the six banger to pull around on the highway. My 2003 G35 Coupe (6m) used to get between 28 and 30mpg on the same trip.

[jankenpo30]

Yes, weight on the 6cyl kills mpg on this car. I get 19city, 21.5hwy doing about 75mph. 93 octane, Mobil 1 0w-40 only.

But I read the sticker on the car, I knew what I was getting & wasn't buying this car with mpg in mind. Obviously, yes, it be nice to have more.

[83wildcat]

jda1015 - When you mention "city" mpg, it’s hard to really compare as one person's idea of city driving might be different than another’s. To quantify what your city driving is, perhaps reset your "Average Speed" in the trip computer and see what it reads after a tank of gas. This will also take in to account the drop in your overall speed due to stop lights, traffic etc. I have a '06 M35X and I live in the outskirts of Seattle and with an average speed of 25 to 28 mph (typical per the trip computer) and I get about 17 mpg. This might drop to the mid-15's when my average speed drops to the low 20's.

I've also been comparing my mpg swapping between 87 octane and 92 octane and over the last 4 tanks this is what I've been getting:

87 octane: 17.26 mpg @ 27.3 mph91 octane: 16.87 mpg @ 25.7 mph87 octane: 17.45 mpg @ 26.9 mph91 octane: 17.60 mpg @ 28.2 mph

So at best it might seem like a push for 87 octane vs. 91 octane.

I've had limited true open highway experience, but based on the one trip I took I got 24.6 mpg @ 66 mph (per the trip computer).

Before anyone criticizes my mpg obsession, I understand these cars were not made for good mpg and I don't have an issue with the mpg. I'm just an engineer who likes to be able to measure a machine's performance. I don't have a dyno, so checking mpg is as close as I can get. Also, knowing what my mpg is under certain circumstances allows me to really run down my tank between fill-ups. When I fill up I usually take 19+ gallons - I haven't run dry yet!

[NightWatch]

Yes, weight on the 6cyl kills mpg on this car. I get 19city, 21.5hwy doing about 75mph. 93 octane, Mobil 1 0w-40 only.

But I read the sticker on the car, I knew what I was getting & wasn't buying this car with mpg in mind. Obviously, yes, it be nice to have more.

I did read the EPA estimates on the sticker when I bought the car, however this is the first Infiniti that I've owned that I haven't been able to beat the EPA estimates by a considerable margin - at least when I'm behaving myself

[Q45tech]

Members need to study the parameters of EPA MPG TEST.Note Highway is defined as 55 mph with a rare ocassional SLOW pass to 61 MPH not 70-75 MPH. AC is turned off and zero passengers or trunk weight. Averaged highway speed is 48.3 MPH and MAX ACCELERATION is 3.3 MPH per second [turtle slow]

The REVISED TEST PROCEEDURE allowing 70 MPH OCASSIONALLY [not 71 or 72] reduces the Highway MPG by 1.5-2 MPG from your old EPA sticker numbers. STILL THE AVERAGE SPEED IS 48.3 MPH

http://www.fueleconomy.gov/feg...shtml

[jda1015]

Thanks Wildcat! I'll definitely reset the speed next time I fill up. I totally understand the typical test measurements of fuel economy as well, but I guess it just expected slightly better out of this fantastic ride. I didn't care about the fuel economy either way when I originally made the purchase. Thanks for response!

[jda1015]

I completely agree with you. My previous 04 G35 coupe got great mileage, obviously due to the much lighter weight, but it was a lot more relevant to the advertised EPA as well.

[mkaresh]

TrueDelta conducts a real-world Gas Mileage Survey that's more details than most.

Results for the M here:

Real-world Infiniti M35 / M45 gas mileage

[DashingMax]

On my M45 V8 on Premium (93 octane) fuel, I average between 16-17 mpg. This is in mixed Chicago driving.

If this car had a 6th gear, I'm confident that the Hwy mileage would be much better.