What's your MPG?

[joe maniqz]

I have a 1999 Q45 and it's 12 MPG on city driving!!! Fuel economy .gov listed it at 16 MPG. What do I need to do to get 16 MPG? Clean or replace injectors? The car is near perfect, but it's my first infiniti so I don't have a clue. Please help.

[oldmako]

Start by reading this thread and others on the topic. There are plenty of basic, easy things to check before you start getting cro-mag with the mechanicals.

zer...ately

tirespsiair filtermafright footaccel habits - guys that consistently blast of the line decel habits - guys that carry power to a yellow or red light and brake latejunk in trunk - spent uranium capsules, nuke fuel rods, diesel crank batts etcwhere ya goetc etc

I don't pay much attention to US Gubmint estimates as probably less than 5 percent of the population equals them. In my opinion, those numbers are fiction unless you always drive downhill. But 12 mpgsucks. 16 is baseline worstest I ever see and that's when wailing on it.

12 mpg at 4.50 a gallon.....makes one want to buy a bike!

[joe maniqz]

checked the air filter and it's clogged with dirt...gonna go out and buy a new one...i read here somewhere that k&n filter gave his car a boost on it's mpg...maybe i'll try that...then off to get a bb44k, if i can find one, if not i'll go with techron...nope, no nuke arsenal at my trunk, it's practically empty...i also up my psi to 40 on all fours...thanks.

[Q45tech]

One thing to always remember is EPA MPG numbers are tested on a special dyno not the real world...................recent revisions of the METHOD have resulted in a 1-2 MPG decline in numbers after revision so 14 MPG in rural city might be closer to truth.

The other problem is gasoline is not used in testing but a special "INDOLENE CLEAR" fuel to avoid refinery to refinery variations.E10 [ethanolized fuel] is at least 3.3% worse than conventional gasoline in MPG so 13 MPG CITY might be normal.

The only factual test is to fill up until it dribbles out then drive 200 miles [no stopping no ac] at a steady precise 60mph then refill again until it dribbles out and DIVIDE.

[maxnix]

.i read here somewhere that k&n filter gave his car a boost on it's mpg....

You didn't read that here! Avoid K&N and go with OEM from

http://www.infinitipartsusa.com

http://www.bgfindashop for your BG44K or use Redline SL1

[NightRiderQ45]

You didn't read that here! Avoid K&N and go with OEM from

http://www.infinitipartsusa.com

http://www.bgfindashop for your BG44K or use Redline SL1

Go with Redline. BG44k is a waste of money since they changed the formula. I think they sell it at pepboys.

[qship96]

Redline Si-1 can be purchased on amazon for $63 DELIVERED PRICE to your door for a case of 12, much better deal than purchasing locally at Poopboys, etc for $8.99 plus your state tax, time,and gasoline and wear and tear driving to get it!.....basically 1/2 price.

I now have enough Redline products stocked to last til the Q gets put to sleep! Cases upon cases of motor oil, transmission fluid, gear oil, injector cleaner-purchasing in bulk off the internet, especially during special promotions, nets you a superior product at prices unavailable in local brick and mortar retailers.

[goody90q45]

I have a 1999 Q45 and it's 12 MPG on city driving!!! Fuel economy .gov listed it at 16 MPG. What do I need to do to get 16 MPG? Clean or replace injectors?

I go through full tanks of gas with 100% city driving averaging 35-45 mph 90% of the time and get 13.5 mpg in the 90Q and 14.5 mpg in the 94Q. Both are well tuned and there isn't much I can do to squeeze out better fuel economy. Where you're living in the San Fernando Valley there's a lot more (a whole lot more) stop and go traffic than in podunk Sacramento. Your only getting 0 mpg when you sit at a red light or are creeping forward at a busy intersection.

How's your mileage on a long freeway run (to Vegas)? I think this would be a fairer test. If you're in the 20-22 mpg range your engine is probably running well. If your getting too much less than that then you may have a problem. All the advice you've gotten is great and you should be doing these things on a periodic basis anyways.

Post up the numbers from your last smog check. They'll tell us a lot.

[jdm94sir]

yep that what i get in my 00 q4512-14 cityand 17-19 high wayi still think its time for a tune up. plugs and efi servise would not hert

[maxnix]

Idle = 0 mpg

Steady heighway at 80 mph = 22 mpg

Mix, somewhere in between, depending on fuel, weather, traffic, temperature, etc.

[jasonhirt23]

Why not use K&n filter? I just bought a 1993 q45....does it not benefit the car or not good? Also, what about iridium spark plugs? Are they worth putting in for gas mileage and etc.?

[maxnix]

Why not use K&n filter? I just bought a 1993 q45....does it not benefit the car or not good? Also, what about iridium spark plugs? Are they worth putting in for gas mileage and etc.?

You need to pull up a chair and do lots of reading.

Neither of those have any benfit over OEM specified items. K&N actually has substantial downside.

[qsiguy]

Here's a screenshot of my MPG, right side, 3rd one down...

Just kidding, that's was a WOT run. Unless I am really careful (rarely post turbo) I average about 14 mpg. I can get up to about 18 if I stay out of boost and never go WOT.

[MinisterofDOOM]

I'm pretty impressed with my Q's ability to return a consistent 17mpg (combined) even with the 4.08, NICO tune, and my not-remotely-conservative throttle habits. I'm pretty confident I could get above 20 combined if I drove like a sensible person. But why on earth would I want to do that?

Why not use K&n filter? I just bought a 1993 q45....does it not benefit the car or not good? Also, what about iridium spark plugs? Are they worth putting in for gas mileage and etc.?

OEM intake draws cool, dense air from a good location. A cone filter sitting in the engine bay will only be a downgrade. A K&N style filter might feel more powerful after startup but, once you're up to normal operating temp, the engine bay is soaked in heat. Stock intake takes air from outside the engine bay, avoiding that problem. At speed, it has a nice supply of fresh, cool air. A K&N cone filter doesn't.

[DoinkMobb]

When I first bought the car, I was getting 19 mpg on 15" Enkei rims and an erratic idle.

After a plenum job and a through overall maintenance regiment AND 18" G35 rims, I was getting low 13's. At the time I wasn't driving much because I was car pooling with two other guys. I thought the poor mileage was due to having two extra people in the car and driving in some pretty bad stop and go morning rush hour traffic. And I figured heavy 18" rims with wider sticky tires didn't help.

Well the mileage kept slowly getting worse...the final straw was when I was down a 1/4 tank after about 30 miles. Something was amiss. My idle was too high (close to 900) so I adjusted to about 550. Re-cleaned MAF sensor and bent pins to tighten MAF connection. Car instantly felt "right" again.

The next few weeks, mileage started going back up - low 14's, high 14's, low 15's. Alright, I can deal with that. That's 100% city driving by the way, I rarely drive on the highway.

Now I'm getting over 17 mpg for some reason. I'm not complaining, just thought it was weird that mileage keeps going up.

[Trumpkin]

My dragon tc and shift kit killed mine, about 10!

[mcrews]

I have an 02 F50 Sport with factory rims w/ 255/45/18 tires ay 39 psi. I have removed the rear muffler. I have 150k miles. and service it religiuoly.I drive a lot of freeway. Just drove Santa Monica CA Van Horn Texas. I got 24.9 mpg at 72.4 avg speed over 8 hours. with cruise and 91 octane. I typically get 23-24 on the road.around town I get about 17mpg

[MinisterofDOOM]

My dragon tc and shift kit killed mine, about 10!

Odd. I wonder if something else is wrong? Wes is always touting the fuel-economy benefits of high-stall TC over the 4.08...I'd expect you to be doing much better than 10.

What shift kit are you running? I've been giving it more and more serious consideration lately. Stupid RE4 needs those shifts tightened up somehow.

[Q45tech]

Just shows you cannot believe much of what you read here or anywhere concerning fuel improvements after ANY OEM MODIFICATION.

Afterall the factory had 3 engineers spend 2 years [cost $2 million] going over the designs of the prototypes looking for any ways to save even 0.5 MPG to avoid/ even reduce the gas guzzler tax payment of $2100 per Q45 sold.

That was 2 million to US government in the launch year alone or $2 Million more than if they had found that 0.5 MPG.

Only does the Q41 with smaller engine and weight avoid the gas guzzler tax increment.

[maxnix]

Only does the Q41 with smaller engine and weight avoid the gas guzzler tax increment.

And in real world driving, the true difference is about 1.0 -1.5 mpg.

[MAX_POWERS]

I get around 13mpg city on my 99 Q. My Q came with a K&N drop in filter when I bought it and have not had any problems. I read here that the oil on the filter is suppose to to get the MAF dirty. I have not had that problem with in the 3 years I owned my Q. I cleaned and re-oiled the filter last summer.

[maxnix]

My Q came with a K&N drop in filter when I bought it and have not had any problems. I read here that the oil on the filter is suppose to to get the MAF dirty. I have not had that problem with in the 3 years I owned my Q. I cleaned and re-oiled the filter last summer.

You will. The last thinkg an engine wants in front of a hot wire MAF is an oiled filter element.

Also it is costing you engine life as K&N doesn't filter as well as OEM paper.