Can a 2002 Q45 get 31mpg on the freeway......

[mcrews]

THe 2002 Q45 weighs 3801lbs and a posted 340hp. Both were class leading numbers in 2002. It also had a 2.76 rear end ratio and drag coeffient of .30

The epa highway of 23 seem on the low side. a 31 mpg would represent better than a 30% improvement over the epa.

[MinisterofDOOM]

For comparison, the 6th gen Maxima, which weighs in the 3200-3400lb range and makes 265hp with a Cd of .28 manages 32 at 80mph highway cruise. The Q idles much lower, with the Max coming in at about 3200rpm at 80mph if I recall.

That would lead me to think you should be able to at least approach 30mpg in the Q on the freeway alone. Should definitely be able to exceed 23. The Maxima is only rated at 27 highway. So if you can beat the Q's EPA 23 by the same 5, you're looking at a much more reasonable sounding number.

EPA ratings are a joke anyway. I've never owned a car that didn't do significantly better.

[mcrews]

MinisterofDOOM,

I had actually pulled an 06 Maxima to compare from one of the used car compare sites.(Kelley06 maxima weighs 3493lbs and gets 265 hp. epa is 26 highway. the rear end is 2.44(wow).an interesting statistic was interior size the 02 Q is 102 cubic ft and the 06 Maxima is 119 cubic ft!

In doing a comparison of similar cars I did a weight to Hp ratio to see which car was caring the least pounds per Hp. I realize that this is a very simplistic ratio because rear end ratios also play into the mpg formula.but here are some intersting ratios05 vette 7.947 lbs per hp05 BMW 760 V12 10.7802 Q45 11.1906 chysler 300C 5.7 hemi 11.9006 acure RL 13.8306 maxima 13.1803 lexus 430 13.6009 sentra 20.92the sentra only makes 140 hp and weighs 3920!!!!but has a hwy of 34epa

probably the only factual thing you can take away from these ratios is that there is a lot of aluminuum and alloy in the Q.

I have consistantly gotten 25 to 27mpg in the Q on road trips. Part of that is driving style and part is the 255/45/18 as opposed to the 245 stock size.THe Q has a mpg screen which helps in keeping an eye on the mpg while driving. I have ordered a ScangaugeII which hooks up thru the obdII port to provide more information.

[MinisterofDOOM]

MinisterofDOOM,an interesting statistic was interior size the 02 Q is 102 cubic ft and the 06 Maxima is 119 cubic ft!

And that's exactly why most family cars these days are FWD. FWD packaging is so much simpler and more compact and allows for significantly more interior space in a comparably sized car.

Funny thing is the '09 Altima actually has more interior space than the '09 Maxima.

Scangauge type tools are the ONE instance I prefer OBDII. So much readily available info compared to OBDI.

[Q45tech]

Weight does NOT mean much at a steady 55 mph, except in rolling friction of tires. Obviously tire tread compound, design and alignment can affect things 30% alone.

Very Hard skinny tires aligned perfectly and inflated to near max 42 or 49 psi [depending on 44 or 51] can do wonders.

"according to a study by the California Energy Commission. This same agency concludes that in most states, only 12% of the tires in use would be considered fuel efficient".

Heck Nitrogen filling can improve MPG by 2-4%.

I would not be surprised at a 2002 Q being able to get 10% better [55mph MPG] than an early Q..................as the speed increased the difference between 15" and 18" tires and worse CD would narrow the difference some.

Lots would depend on the precats and cats backpressure as the two age since displacements are equal and top gearing is 9%.

[qship96]

How does nitrogen filling provide 2-4% increase in mpg over a similar psi fill of air????

[mcrews]

How does nitrogen filling provide 2-4% increase in mpg over a similar psi fill of air????

Q45tech, My local tire shop does nitrogen...I'll check into that.I do run 42-44psi already which probably accounts for some of my current mpg success.

you are correct about weight in context of moving down the road. My point had been that the platform is somewhat efficent in comparison to similar

I'm probably not goin to run tall skinny tires...... but running the 255s works for me

[Q45tech]

Road to tread and tread to sidewall Frictional losses show as heat in tires.Using Nitrogen from day one displaces interior oxygen [only 22% +WATER VAPOR] WHICH CAUSES OXIDATION OF RUBBER COMPOUNDS CHANGING THEIR MOLECULAR STRUCTURE AND FRICTION COEFFICIENT.

Easy to measure running/rolling tire temperature vs ambient to determine friction coefficient.

Remember tires are the highest loss component in friction losses between engine and road interface. All that friction get converted to heat.

Using Nitrogen after tires have been abused with compressed air may not yield as much improvement as from day one.

Lot really depends on the roughness and composition of road as to how tires react. Obviously concrete vs asphalt depends on the stone/clump size microscopically.http://hyperphysics.phy-astr.g...l#coe

" car weighs 4,000 pounds (1814.369 kg), and the tires have a CRF of 0.015. The force is equal to 4,000 x 0.015, which equals 60 pounds (27.215 kg). .....you know that power is equal to force times speed. So the amount of power used by the tires depends on how fast the car is going. At 75 mph (120.7 kph), the tires are using 12 horsepower, and at 55 mph (88.513 kph) they use 8.8 horsepower. All of that power is turning into heat. Most of it goes into the tires, but some of it goes into the road (the road actually bends a little when the car drives over it).

Each HP is 12,000 BTU so 8.8 = 105,600 btu enough to comfortably heat a 4 bedroon house in 0F winter.

Measure tires [IR gun] after 15 minutes at 55 mph you might get surprised.

Don't confuse the geater frictional losses from accelerating on a dyno vs steady state [1.5% vs 15>22%].

[elwesso]

mcrews, just wondering, when you claim 31MPG, did you reset the MPG calculator on the dash during a steady cruise, or is that average over say a tank of gas, where you divide the # miles driven/gallons used.

Just curious on how you calculated it, a number is only as good as the place it came from.

[mcrews]

Elwesso,I have a 7 mile stretch of hwy 80 from sacramento to Roseville CA the is relatively flat. I have two overpasses that I use as start and end. I reset the onboard mpg screen as I go under the first overpass. I then exit the freeway and come back in the opposite direction. I reset the sreen as I start the run in the opposite directionI also set the cruise control for the same speed each way.I havent actually gotten 31 yet. My best one way run is 30.8mpg and my best combined run is 29.9mpg

[qship96]

Elwesso,I have a 7 mile stretch of hwy 80 from sacramento to Roseville CA the is relatively flat. I have two overpasses that I use as start and end. I reset the onboard mpg screen as I go under the first overpass. I then exit the freeway and come back in the opposite direction. I reset the sreen as I start the run in the opposite directionI also set the cruise control for the same speed each way.I havent actually gotten 31 yet. My best one way run is 30.8mpg and my best combined run is 29.9mpg

Well that short flat stretch is certainly not indicative of "highway mpg" the way most measure it , and certainly not a comparable result to EPA numbers.....go for a real highway trip of a few hundred miles including normal hills and speed adjustments for traffic and report back! I can duplicate 23mpg on a 155 mile trip at 75mph from Baltimore to Ocean City Md over and over.....22.xx mpg from Baltimore to T3Atlanta and within .25mpg difference on return trip

[elwesso]

Well that short flat stretch is certainly not indicative of "highway mpg" the way most measure it , and certainly not a comparable result to EPA numbers.....go for a real highway trip of a few hundred miles including normal hills and speed adjustments for traffic and report back! I can duplicate 23mpg on a 155 mile trip at 75mph from Baltimore to Ocean City Md over and over.....22.xx mpg from Baltimore to T3Atlanta and within .25mpg difference on return trip

I agree... I think my Q gets a little better than the highway MPG rated, maybe 1-2 MPG better.. Ive seen 23MPG before over 400 miles..

Unless you're averaging over 100 miles, I kind of consider it anecdotal.... I could coast down a small grade for 30 miles in neutral and say I got 50MPG... kind of the same thing...

[Infinitiguy19]

No offence but if you are driving a Q45 (V8) why are you worried about MPG's? Hell my car can get 10 MPG and I would still drive it.

[mcrews]

Well that short flat stretch is certainly not indicative of "highway mpg" the way most measure it , and certainly not a comparable result to EPA numbers.....go for a real highway trip of a few hundred miles including normal hills and speed adjustments for traffic and report back! I can duplicate 23mpg on a 155 mile trip at 75mph from Baltimore to Ocean City Md over and over.....22.xx mpg from Baltimore to T3Atlanta and within .25mpg difference on return trip

yuk yuk.... let me tellem jethro.....

Actually you comment is totally reflective of anadotal 'testing' & dyno-butt!

I really just assume you guys were familiar with the concept of testing....but let me review with you (you remeber how you bust everybodies a** when the say 'well it feels faster") how A-B-A testing works and why:

Any testing that can be affected by driver input - eg. city driving is the worst - is dramatically less scientific. A driver may unconsciously change driving style to get the desired result (experimenter bias). An ideal experiment would be double blind.

Failing to "remove the driver" as much as possible from the test is a huge red flag and we should be very skeptical of conclusions made.

3) The route should be devoid of other traffic, to avoid significant aerodynamic impacts of vehicles ahead or overtaking.

4) Weather conditions should be as calm and stable as possible (wind gusts/changes in wind speed will throw off results)

5) The route should be as flat & straight as possible.

6) Bi-directional runs should be done to average out effects of grade/wind, if present. Meaning, test on the route in both directions.

7) Use A-B-A comparisons. That means establishing a baseline (the first "A" set of runs), more test runs after making a change (the "B" set), and then additional runs after undoing the change (the last "A" set).

Why do A-B-A testing? Undoing the change and immediately re-testing the final "A" set increases confidence that any difference seen in the "B" runs was caused by the modification, and not by other uncontrolled factors.

8) A-B-A comparison runs should be done immediately one after the other to minimize the effects of changing weather conditions, vehicle temperature, weight, fuel quality, etc.

Really, I just thought you'd recognize 'testing' as opposed to some silly trip.

but the hypocracy is a little overwhelming

[mcrews]

I agree... I think my Q gets a little better than the highway MPG rated, maybe 1-2 MPG better.. Ive seen 23MPG before over 400 miles..

Unless you're averaging over 100 miles, I kind of consider it anecdotal.... I could coast down a small grade for 30 miles in neutral and say I got 50MPG... kind of the same thing...

Yeah, you could do that wes, but that's lying....... Why don't you google earth that section on US I - 80 first......and wes, how is lying and going one way 'kinda' the same thing?

I think I was clear, but let me repeat....'i set the cruise both ways for the same speed."

[qship96]

You are missing the point....who gives a rats azz how many mpg one can squeeze out on a 7 mile flat stretch of highway at a steady speed ???? Real people driving in real world conditions are what matter-take a long highway trip under REAL conditions like you do when you are traveling interstate and report back.Guarantee you your results will be much lower mpg than your useless controlled test.

[mcrews]

wow, do you alway get pissy when you are proven dead wrong?

You are missing the point....who gives a rats azz how many mpg one can squeeze out on a 7 mile flat stretch of highway at a steady speed ???? Real people driving in real world conditions are what matter-take a long highway trip under REAL conditions like you do when you are traveling interstate and report back.Guarantee you your results will be much lower mpg than your useless controlled test.

hey, brighteyes, testing is about proving something works, it's about baselines.

no jethro YOU miss the point... I have two previous post that showed long trips and great mpg

zerothread?id=367542

this trip to Salt Lake city and back include 5 days of intown driving (oh I mean REAL person driving)

zerothread?id=193243

or maybe this post that included a 6000 ft mountian range ----- too REAL

or the 2 round trips to texas and back where I averaged 26+

Or the 5 other times I have posted in a existing thread that I get 25+ mpg on the road ie round trips to San Fran from sacto and back.

so back to your rats azz........Mxxxxxx........when you make changes you test them. you dont fuxxin drive to boston.oh back to testing, you test each change seperately......to make sure your butt --- dyno isn't pukerin too tight with excitement.

I'll take that bet jack, put up or shut up, I call.

[Infinitiguy19]

so back to your rats azz........Mxxxxxx........when you make changes you test them. you dont fuxxin drive to boston.oh back to testing, you test each change seperately......to make sure your butt --- dyno isn't pukerin too tight with excitement.

You drive to Boston?

Bypassing the word filter is grounds for BANISHMENT!!!

[qship96]

You drive to Boston?

Wonder how many times he has to pull to the side of the highway on that trip to pour a quart of oil in? No wonder he likes to only do 7 mile tests!!!!!

[mcrews]

No offence but if you are driving a Q45 (V8) why are you worried about MPG's? Hell my car can get 10 MPG and I would still drive it.

paul.....because I can. why do you sell stuff in you signature?

but didn't you just say this on another post less than 2 days ago?

Either way this is not my cup of tea. I prefer the FGY33 rear spoiler with a front spoiler of some sort under the front bumper. Hell I might sound crazy but I would love to get some undercarriage plating to improve aerodynamics.

maybe something like this:





because the turbulance caused by this is not good...



but this "undercarriage plating to improve aerodynamics." was what I was testing:





So for everybody but jethro,when you make a change you can do 3 things:1. use your butt dyno 2. do a real world 1000 mile drive to boston 3. do A-B-A testing

The grille block got me to 28.5the front underbelly pan got me to 30.

[Infinitiguy19]

paul.....because I can. why do you sell stuff in you signature?

but didn't you just say this on another post less than 2 days ago?

Either way this is not my cup of tea. I prefer the FGY33 rear spoiler with a front spoiler of some sort under the front bumper. Hell I might sound crazy but I would love to get some undercarriage plating to improve aerodynamics.

Yup you caught me I want more speed and could care less if that results in more MPG. Personally I prefer duel quads but I can live with the Q.

Why do you have a problem with me trying to generate money for myself and others in exchange for posting and doing the best I can to help people? Your better off not changing the subject because it shows weakness.

Why a fake grill though? I mean it reminds me of this:

But it sucks that all these posts will be deleted.

Wonder how many times he has to pull to the side of the highway on that trip to pour a quart of oil in? No wonder he likes to only do 7 mile tests!!!!!

Nice burn.

[qship96]

Big deal a Prius will get you to 45........happy Hanukkah

[elwesso]

man this is more entertaining than monday night football... what could be a better than a bunch of overpaid undereducated people smash into each other? A bunch of probably well qualified, reasonably compensated individuals bashing each other about who's 4000lb car gets better gas mileage.

man, the ends that people will go to try and convince someone on the otherside of the interwebs..

[qship96]

Just having a little fun with the elderly Texas cowboy!

[Infinitiguy19]

Just having a little fun with the elderly Texas cowboy!

I would be careful though because I heard from a source (I will not disclose from fear of a law suit) that you can get sued for things said over the internet. I think I need to consult a IP lawyer on this one. Apparently though some woman posted something about her EX and he sued her....

[mcrews]

couple of thoughts1. you were set up. you' are each so predictable that I knew a could pull you (and your foolish comments) in by posting a question that had an incomplete fact pattern.2. paul you miss the entire point of 'why.....' so i'll explain it to ya lucy....you shoot off a sentence (just like last christmas with the halos) and dis me about mpg. But nobody can dis you about the sig. seems hypocritical....it is.paul quit asking why and start opening your mind. Think about this....if you ever smooth out the front under pan on you car.....you saw it some where ....If you don't give a crap about mpg, then don't post. what have you contributed to this entire post? just negative stuff.3. q96, you were the easy one because you run on one track.....anything off the track you start to heat up. Your more predictable than my ex.4. q96, why would you make this useless comment "go for a real highway trip of a few hundred miles including normal hills and speed adjustments for traffic and report back!" ? hell we had this discussion over on the M site.5. The really sad part is that this forum has really lost it's luster compared to other sites. the site could really be special but too much knee jerk. Instead of encouraging or passing, it's like a core group of post hoes just notching the bedpost.6. See, I did the testing and proving and had the pictures long before I posted. I had the answers before you had the predictable silly comments Merry Christmas

ps: q96 I am very serious ( for a second time) " I'll take that bet jack, put up or shut up, I call."you like to say thinks you can't and won't back up.... put up your keys
Modified by mcrews at 7:58 PM 12/21/2009

[Infinitiguy19]

Eh screw it I don't even know why I waste my time with you and your useless self center posts. I have to start focusing on my projects and G50's ONLY well maybe the occasional FGY33. But I promise from now on I will avoid your posts and any other F50 posts like the plague.

Hey can some one prevent me from posting in Mcrews posts and F50 posts in case I some how get that itch?

But last Christmas with the Halo's (Cough:BMW rip off:Cough) I posted more info on them that I found out and you neglected to post, and you got your panties in a bunch over that. Man your more one sided than a 1 way street.

[Marv007]

Mcrews,All the rifgt answers to all the wrong questions don't get you anywhere.There is nothing quite as frustrating as giving someone the correct answers to the correct questions then they still don't get it. Many people on this forum tried to help you to not be as ignorant. When you have the correct information and still get it wrong then it's called stupidity. I just had to vent that.

[qship96]

Love the Forrest Gump line....."Stupid is as stupid does"

[marksport]

Why is it that this forum seems to be so much F50 bashing? My brother has owned both the G50 and Y33, and I own two F50. All are great cars, all have their good points and flaws. All have been more reliable that the Audi and BMW that he has since owned. I look at the Lexus forum and don't see this kind of infighting, and a lot more productive postings. Many of the members over there are doing turbo and supercharging projects. There really is a lot of bashing on the F50 here on many different threads.