Am I driving at the right RPM on freeway?

[NSXER119]

Hi, everybody
I just have a question here....I had a long trip yesterday (about 500 miles back and forth) with my 92 NSX. I found out that the car only can run about 24 mile per galon on freeway (no local and with some uphill and downhill but not very steep), and I am driving about 75 to 85 mph. I was using the top (5th) gear most of the time except for some uphill. Do you guys think that I was on the right gear on the freeway? or I can save some gas if I was on the forth gear?
I have checked the faq and some owners can run about 26-28 mpg on freeway, do you guys think that there is something wrong with my car?
any suggestion would be great
Thank in advance

 

[Edwardo]

I believe if you were going 65-75 mph, never shifted into fourth, and you were on level roads you may have averaged a few more miles per gallon.

 

[MiamieNeSeX]

24 MPG............ geez how much more you want to squeeze of the car. Buy a Hugo jk LOL

 

[docjohn]

I get about that~23mpg street,of course at the track more like 5-6.

 

[ak]

I got somewhere around 28-30mpg out of my 750 mile trek from Chicago to DC. Maybe it's the 91 octane pee water you have to use in California. You weren't using regular gas right? It helps to use cruise control also.

 

[NSXER119]

Thanks for all the comments...
I am using 91 octane gas....
you guys can get higher octane gas in other states?
I just put a K&N filter and a fuelmax magnet on the fuel line...
what else you guys think I can do to improve gas mileage? maybe valve adjustment, or replace spark plug and wire, my car has about 68K miles and I haven't replace the spark plugs and wire yet....

 

[MvM]

If 1 US gallon is still 3.7854 liters and 1 mile is still 1609 meters then I never even come close to that.
On average I will do 18.82 miles per US gallon or 8km per liter.
The highest I ever got was 22.70 miles to the gallon. And it has been my habbit to write down all stats (litres put in, price, mileage and total milage) on every tankstop for years.
I'm using 95octane, known here as "Euro loodvrij".

 

[stevefromatl]

24 MPG............ geez how much more you want to squeeze of the car. Buy a Hugo jk LOL

Exactly! What do you expect for driving 80 mph? If you want gas mileage you'll have to compromise speed.

 

[DanO]

maybe valve adjustment, or replace spark plug and wire, my car has about 68K miles and I haven't replace the spark plugs and wire yet....

You may consider doing the scheduled 60k service. I think this takes care of a valve adjustment, fuel filter, and plugs. FYI there are no spark plug wires in the NSX to replace--direct ignition BABY!!!

DanO

 

[NSXER119]

Forget to mention...my car only runs 15.5 to 16.5 mpg almost every time i fill up the gas tank. I drive about 90% local...and I am living in San Francisco where is quite alot uphill and downhill, so I think it should be normal. However, the gas is quite expensive now.. so I want to figure out if I can save some money on gas hehe....
I guess I have to live with it because I love my car so much and I enjoy driving her very very much.......I would pay even double of the gas if I need as long as I am driving my NSX
thanks a lot.....guys

 

[nsxtasy]

First of all, I think it's legitimate to wonder whether a car is operating normally based on the mileage obtained. Those of you who are so quick to criticize him for asking should be ashamed of yourselves.

I had a long trip yesterday (about 500 miles back and forth) with my 92 NSX. I found out that the car only can run about 24 mile per galon on freeway (no local and with some uphill and downhill but not very steep), and I am driving about 75 to 85 mph. I was using the top (5th) gear most of the time except for some uphill. Do you guys think that I was on the right gear on the freeway? or I can save some gas if I was on the forth gear?

To maximize your mileage, you should be in the highest gear possible without lugging the engine. (This is the opposite of maximizing performance, for which you should be in the lowest gear possible without exceeding redline.) So your mileage would be higher if you kept it in fifth than if you drove it in fourth.

I agree with DanO's advice to do the 60K mile maintenance which you have apparently not done. There are various reasons for doing the scheduled maintenance on time - not only to prevent things from failing, but also to maximize performance and efficiency so that the car can run as it should. Spark plugs are specified in the owner's manual to be replaced at 6 years or 60K miles, whichever comes first. Yours are now six years overdue!!!

Once your car's scheduled maintenance is performed, I think you will find that you get better gas mileage. I have driven long distances and gotten 28-29 miles per gallon going 75 to 85 mph. However, that was with no stops and no city driving - get in the car, get on the interstate, drive 450 miles (e.g. Indiana to Atlanta, which includes some uphill and downhill stretches), and pull off into a gas station.

I am using 91 octane gas....
you guys can get higher octane gas in other states?

Yes, we get 93 octane premium here in Chicago, and I think that's true of most states except in California or in high-altitude areas (e.g. Colorado) where the additional octane won't help due to the thin air.

 

[MiamieNeSeX]

Re: Re: Am I driving at the right RPM on freeway?

First of all, I think it's legitimate to wonder whether a car is operating normally based on the mileage obtained. Those of you who are so quick to criticize him for asking should be ashamed of yourselves.

Lighten Up

 

[nsxtasy]

Re: Re: Re: Am I driving at the right RPM on freeway?

Lighten Up

That's exactly the point I'm making to people like you (and stevefromatl) who are so quick to criticize others!!!

Maybe you should try taking your own advice (but at least YOUR original comment had a LOL with it, unlike steve's)...

 

[MiamieNeSeX]

Ok then, so if he is getting 24 MPG now in a $25,000 to $30,000 11 year old 270 hp sports car, and he does the 60,000 tune up at a cost of $?, how much does it cost to get an extra few miles per tankfull.

 

[NSXROX]

Just for comparison...
I drove from Tampa to Baltimore this past January and averaged 27 mpg going 80-90 mph. And yes, I was in 5th gear the whole time.

 

[nsxtasy]

Ok then, so if he is getting 24 MPG now in a $25,000 to $30,000 11 year old 270 hp sports car, and he does the 60,000 tune up at a cost of $?, how much does it cost to get an extra few miles per tankfull.

It's not just a matter of gas mileage. If you don't do the maintenance on your car when it's due, chances are that you are going to pay more in the long run, due to repair issues, etc.

As my mechanic likes to say about whether or not to do scheduled maintenance, "You can pay me now, or you can pay me even more later. Your choice."

Skipping the scheduled maintenance - on ANY car that is worth keeping for a while - is extremely foolish and economically unwise.

MiamieNeSeX, you are giving terrible advice by telling people not do to their scheduled maintenance. Of course, they're the ones who will have to pay for the repairs that are caused by lack of maintenance, not you. Fortunately, most of us know that this is bad advice and don't treat our cars like cr*p the way you are recommending.

 

[MiamieNeSeX]

It's not just a matter of gas mileage. If you don't do the maintenance on your car when it's due, chances are that you are going to pay more in the long run, due to repair issues, etc.

As my mechanic likes to say about whether or not to do scheduled maintenance, "You can pay me now, or you can pay me even more later. Your choice."

Skipping the scheduled maintenance - on ANY car - is extremely foolish and economically unwise. MiamieNeSeX, you are giving terrible advice by telling people not do to their scheduled maintenance. Of course, they're the ones who will have to pay for the repairs that are caused by lack of maintenance, not you. Fortunately, most of us know that this is bad advice and don't treat our cars like cr*p the way you are recommending.

Listen hot shot, I never told anyone not to maintain thier car in the correct and or recommended manner, but I do find it funny what some people worry about, and in my opinion 1 or 2 miles more or less when you are driving the kind of car that we drive is petty,

 

[Edwardo]

I did not realize you had not done the 60k checkup. As others have mentioned, one of the items replaced in your engine during said service is the spark plugs(which is obviously very important to fuel mileage).

Another small item to check before a trip is your tire pressure. Make sure your tires are inflated to the proper level.

 

[stevefromatl]

Re: Re: Re: Re: Am I driving at the right RPM on freeway?

That's exactly the point I'm making to people like you (and stevefromatl) who are so quick to criticize others!!!

Maybe you should try taking your own advice (but at least YOUR original comment had a LOL with it, unlike steve's)...

Sorry, I didn't mean for it to sound harsh. that wasn't my intent. I just thought it was strange why he was worried about something being wrong with his car for being a few miles per gallon off on a trip when there are constant variables that need to be accounted for. Also, gas mileage is usually the last thing I'm worried about when I drive my nsx.

 

[NSXER119]

Thanks for all the comments....
I am going to buy one of the recommended spark plug:
NGK PFR6G-11 or the ND (Nippon Denso) PK20PR-L11
which one do you guys recommended?

 

[docjohn]

I hope the above exchange dos'nt give you the wrong idea.I echo The potential importance of poor gas milage if it should be more for the car and driving style.My milage is on a car with shorties and 4.55 rp and with cams so my milage may be worse compared to other 3.0 l cars.In bygone days acurate mpg was important to gauge performance esp on carb cars i.e. before computers!Many of us get lulled into thinking that these cars are infalible paragons of performance(which they can be )but you gotta maintain them.

 

[POWERED by HONDA]

Wow. The best I've gotten was a trip to Los Angeles and I averaged 25mpg. Other than that ONE trip, I usually get 20-22mpg. But then again, I usually don't like to fill up my tank until the fuel warning light turns on. When I got 25mpg, I filled up the tank right next to the freeway onramp, and filled it back up right when I got off the offramp.

 

[mhoyt01]

great mileage

I was surprised to hear all of your mileages. I came back from a laguna seca track event a couple months ago. 405 miles door to door, 90-95 mph, no stops no cruise, 15 gallons or Chevron 91 octane. = 27 MPG.

I get more when I drive slower too. I do have CT headers, empty cats, and DC cat-back, which probably all help....

Matt

 

[naaman]

Also, isn't it good for gas milege to keep the engine operating near the torque peak?

 

[5inchfatlip]

I'm surprised so many really "watch" the gas mileage. I dont really pay attention to it, I drive the way I drive sometimes hard, sometimes just cruising. The car is meant to be driven and enjoyed, at least IMHO, even at over $2.30 a gallon I still get on it most of the time...