Am I driving at the right RPM on freeway?

[nsxtasy]

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

No, not at all.

 

[nsxtasy]

But then again, I usually don't like to fill up my tank until the fuel warning light turns on.

How low you let the tank get has nothing to do with your mileage, except for a minuscule difference (and a positive one, at that) due to the average weight of your car being ever so slightly lower if you wait that long.

 

[POWERED by HONDA]

How low you let the tank get has nothing to do with your mileage, except for a minuscule difference (and a positive one, at that) due to the average weight of your car being ever so slightly lower if you wait that long.

What I meant by my post was that I usually go weeks before I have to refill my non-daily driver. During those times, I usually drive in all types of conditions (freeway, city streets, have fun at onramps and offramps, canyon driving, etc).

But during that ONE time I got 25mpg, I filled up right before I went on the freeway, and filled up right after I got off the freeway. There was no mixture of driving conditions that could vary the fuel mileage.

 

[Bryan]

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

Torque is roughly proportional to engine efficiency at WOT, but that's not the same as best economy at part throttle cruise. At a given speed you want the throttle as far open as possible for best efficiency. In other words you should be in the highest gear reasonable for the speed. For any highway speed that would be fifth gear (or sixth if you got one.)

 

[naaman]

Thanks Bryan... I'm gonna have to do some follow up research on this... I don't quite understand.

I'm sure what you're saying is true, but I just can't get my head around it.

What it sounds like you're saying is that you want to be as close to wide open throttle at as low an rpm as possible or is "reasonable" to conserve fuel.

Why WOT?

 

[nsx4fun]

NSXER119,
Last year I took a trip to my parents house in Oregon. I drove via cruise control on I5 from Sacramento to Salem Oregon & back. I maintained a 76 mph in CA and a 67 mph in Oregon. I have a '92 wht/blk (5 speed). I was in 5th gear for 99.9% of the trip. On Sacramento gas, I got 24.5 mpg from Sacto to Yreka (or was it Dunsmuir). With gas from very Northern CA and Oregon, I got 28 to 28.5 mpg the rest of the trip. My conclusion is the MTBE (and/or other oxygenates) required in the high density population areas of CA (i.e. Sacto et al) decreases the freeway gas mileage by about 20%. Granted, it is a limited experiment, but thes are my honest results. I hope this info helps.

 

[calexand]

I often find that I want to shift up one time more than available in getting up to speed on the freeway, despite having a 6-speed. I think the top gear is too low.

 

[NSXROX]

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...

Computing MPG from time to time can be a good indicator of engine problems. Thats the only real reason I do it. I'd be surprised if many NSX owners really have to worry about the price of the gas we put in our cars. Although I'm sure the fellas in California feel the pain more than I do in Maryland. Paid $1.67 for 93 octane yesterday.

 

[nsxtasy]

Computing MPG from time to time can be a good indicator of engine problems. Thats the only real reason I do it.

It's also helpful in planning where to stop for gas on a long-distance trip.