29.5MPG!

[SleeprLegend]

Yep you read that right. I drove ~50 miles into Atlanta and got an average MPG of 29.5 as I exited the interstate. I have changed my valve and side cover gaskets, PCV valve (2MPG right there), spark plugs, OEM plug wires, and a short ram intake. I just got my new OEM distributor. This week I will install that, OEM fuel filter, and OEM main plug wire. Once I have all this I will probably be at a higher average MPG. My next trip to ATL I will test it again. BTW this is driving in moderate traffice at 70-85MPH while trying to maintain 80mph.
Later!
Lee

Oh yeah - They technician that test drove my car claims it is faster than his S2K. We will have to wait and see if that is true.

[body9599]

Originally Posted by SleeprLegend

Yep you read that right. I drove ~50 miles into Atlanta and got an average MPG of 29.5 as I exited the interstate. I have changed my valve and side cover gaskets, PCV valve (2MPG right there), spark plugs, OEM plug wires, and a short ram intake. I just got my new OEM distributor. This week I will install that, OEM fuel filter, and OEM main plug wire. Once I have all this I will probably be at a higher average MPG. My next trip to ATL I will test it again. BTW this is driving in moderate traffice at 70-85MPH while trying to maintain 80mph.
Later!
Lee

Oh yeah - They technician that test drove my car claims it is faster than his S2K. We will have to wait and see if that is true.

That's pretty good....wish I could claim the same...Hoovering around 23-24.

[SleeprLegend]

Originally Posted by body9599

That's pretty good....wish I could claim the same...Hoovering around 23-24.

The PCV valve, intake, and Mobil1 have had the most dramatic effect on gas mielage so far. Is that mielage you stated city or highway? I get about 22mpg city, and that is driving hard.
Later!
Lee

[Digger89L]

How can you measure gas mileage on a "50 mile" trip? A more "normal" way would be to fill the tank up (as full as possible) ...then drive it as you normally would (or take it on a long highway trip (say 300 miles) ...then fill the tank up (as full as possible, like the first time) ...then do your math (300 miles divided by, say, 12 gallons = 25mpg). On city driving, I get about 22mpg ...and on long highway trips, from 29 to 32, depending on conditions. (89L Sedan, 360k kms ...original drivetrain)

[body9599]

Originally Posted by SleeprLegend

The PCV valve, intake, and Mobil1 have had the most dramatic effect on gas mielage so far. Is that mielage you stated city or highway? I get about 22mpg city, and that is driving hard.
Later!
Lee

Thats driving to and from work...about 7miles on streets and 24 on the highway...so roughly 1 to 3 ratio of city to highway driving.

[Jeef]

Originally Posted by Digger89L

How can you measure gas mileage on a "50 mile" trip?

not enough information to calculate it accurately.

For example, what if you really topped of your tank as much as you could before your trip. So much so that it couldn't take another drop without spilling over. The you drove 100 miles (50 each way) and refilled. Only this time you didn't completely top it off. There could be a difference of as much of a gallon.

Now on 100 miles if you put 3.45 gallons in you would average 29MPH

But if you topped it off and put 4.45 gallon in to replenish the exact amount you used then you would have only averaged 22.5MPH

Split the diff and top it off with 4 gallons and you would still only avg 25 MPG.

To accurately get your average MPG you need multiple tanks to accomodate for the immeasurable differences in the topping off effect.

[SleeprLegend]

Originally Posted by Digger89L

How can you measure gas mileage on a "50 mile" trip? A more "normal" way would be to fill the tank up (as full as possible) ...then drive it as you normally would (or take it on a long highway trip (say 300 miles) ...then fill the tank up (as full as possible, like the first time) ...then do your math (300 miles divided by, say, 12 gallons = 25mpg). On city driving, I get about 22mpg ...and on long highway trips, from 29 to 32, depending on conditions. (89L Sedan, 360k kms ...original drivetrain)

There is this cool little thing in the dashboard that measures current MPG and gives you average MPG. I reset it right before I got on the interstate and checked the reading when I got off the interstate. It said 29.5. Last time I made the same trip it said 28. When I first got the car I was getting 26 MPG on 300 mile interstate trips.
Later!
Lee

[SleeprLegend]

Originally Posted by Jeef

not enough information to calculate it accurately.

For example, what if you really topped of your tank as much as you could before your trip. So much so that it couldn't take another drop without spilling over. The you drove 100 miles (50 each way) and refilled. Only this time you didn't completely top it off. There could be a difference of as much of a gallon.

Now on 100 miles if you put 3.45 gallons in you would average 29MPH

But if you topped it off and put 4.45 gallon in to replenish the exact amount you used then you would have only averaged 22.5MPH

Split the diff and top it off with 4 gallons and you would still only avg 25 MPG.

To accurately get your average MPG you need multiple tanks to accomodate for the immeasurable differences in the topping off effect.

I guess you have not seen the information center on the G1. Mine does Distance Till Empty, a seperate trip odometer, current mpg, and average mpg. It also shows coolant, oil, and washer fluid levels. With this it still keeps track on the mielage between oil changes and mojor service seperately. Pretty cool for 1988.
Later!
Lee

[Legend_Master]

hey lee thats great I only got 19-20 in the city and 23-25 on the highway. Not all the models of the G1 come with the center console info thing only the LS's I think, but I fill mine up till the pump stops and check my average MPG everytime I refill the tank.

[Acurate Legend]

Ya those trip computers aren't acurate at all... never go by those. They jump up and down all the time. Especially only going 50 miles. I can go 10 miles and it would probably show i get 45mpg, very inacurate. Calculate it the normal manual way with a calculator and thats what your real mpg are...

[SleeprLegend]

Originally Posted by Legend_Master

hey lee thats great I only got 19-20 in the city and 23-25 on the highway. Not all the models of the G1 come with the center console info thing only the LS's I think, but I fill mine up till the pump stops and check my average MPG everytime I refill the tank.

Next time you are going to drive on the interstate put the display to average mpg and pull the button down and hit one of the 3 buttons under it to reset. I believe the right button will make a beep noise. Sit back and watch that while you are on the interstate. I reset mine for interstate tests, but now I am going for a 1 month average of my regular driving.
Later!
Lee

Added: I am not 100% on which cars have the info center but my 1988 L coupe does.

[AndaHeart]

Originally Posted by SleeprLegend

There is this cool little thing in the dashboard that measures current MPG and gives you average MPG. I reset it right before I got on the interstate and checked the reading when I got off the interstate. It said 29.5. Last time I made the same trip it said 28. When I first got the car I was getting 26 MPG on 300 mile interstate trips.
Later!
Lee

Hey Lee, i would recommend doing the math for a full tank vs miles driven method. I had the info center on my legend (even though it was only an L) and it was notoriously wrong. I'm not sure how it measures your mileage, but mine was never spot on.
wayne

[SleeprLegend]

Originally Posted by Acurate Legend

Ya those trip computers aren't acurate at all... never go by those. They jump up and down all the time. Especially only going 50 miles. I can go 10 miles and it would probably show i get 45mpg, very inacurate. Calculate it the normal manual way with a calculator and thats what your real mpg are...

Actually they are very accurate. When you have just reset it it does jump a lot. I have seen my average mpg as high as 99 before. Keep watching it and it will level off. It will change some as you go up or down a hill, but it stabilizes. It uses every current mpg figure recieved since you hit the reset. Mine is very accurate. I don't do that many long interstate drives right now, but I will start as the weather gets better. I will do a full tank test and compare it to the computer then, but I bet it will be close.
Later!
Lee

[Legend_Master]

Originally Posted by SleeprLegend

Next time you are going to drive on the interstate put the display to average mpg and pull the button down and hit one of the 3 buttons under it to reset. I believe the right button will make a beep noise. Sit back and watch that while you are on the interstate. I reset mine for interstate tests, but now I am going for a 1 month average of my regular driving.
Later!
Lee

Added: I am not 100% on which cars have the info center but my 1988 L coupe does.

I didnet have that on mine and I sold my Legend

[Jeef]

I don't think anybody is questioning that you were capable of obtaining 29MPH, just that the information used to obtain that number is no where near sufficient data.

FWIW, I have a similar display in my car - and while for the most part it's accurate. I still check it the old fashion way with a calculator and a complete tank of gas.

I wish my car got that fuel economy, be interesting for you to post updated data over the next couple of weeks.