I've calculated the actual vs DIC for my car for about 8 tanks the first summer I got it and it was <0.5mpg out each tank so I stopped calculated.

If you ran 50mph you'd likely do even better. I've found my car can get to 34-35mpg on a 2-lane highway running about 60mph on a good day. If I increase the speed much at all it quickly drops to around 29mpg which it seems to hold for any faster reasonable highway speed.


Is this based on you never resetting the DIC. I don't believe for a minute the DIC properly calculates the mileage forever. There seems to be a certain distance it stores for calculations then the new over-writes the old.

I did a trip from here to Tenessee and back. The whole trip was almost 2500miles. I reset the DIC when I hit the highway at the start of the trip. After driving about 1500 interstate miles, I ended up in Chattanooga and the DIC read about 29mpg. All stops this part of the trip were just off the interstate a bit to visit a site and then right back on again. I then drove around a couple of back mountain roads and also visited tourist sites going about 200miles or so and by then the DIC read 21mpg. I then drove about 750 miles straight home and the DIC read 29mpg again.

These numbers make no sense so the DIC can't be an average of forever but rather must be some fixed distance. Likely something like 500 miles or 750 miles or some distance that would be just more than a tank of gas.

Peter

 

i've manually checked my MPG's and have gotten anywhere from 31-33 mpg highway. My DIC usually says 1-2mpg higher then what i actually get. Mods in sig btw

 

 

I make the Reno to Las Vegas trip 2 times a year and I always seem to get 29-30 mpg, It is 450 miles one way and I can do it on 1 tank. A4 3.15 gears 70 mph using CC.

 

I bought my car in Michigan and had to import it here.


So now I think we can all agree that the vette gets great highway mileage. It seems to me that there are only 3 more keys to better mileage.

1) Slower acceleration. But who wants that ?

2) Lower idling speed at stop lights. I think this is the biggie. If we could find a way to drop the idle from 700 rpm to 450, for instance, (without knocking out the main bearings) our overall gas mileage would go up considerably. Sitting with 5.7 cubic litres idling at 700 rpm is the big culprit to lower mileage.

3) I also try to gear up often. My average RPM stays around 1200.

Dan


http://teachmedrums.com

 

after my mods my DIC says i get 31-32 on the higway, but its more like 27mpg after the manual calculation

 

I put almost 900 miles on the vette last weekend..Dallas to College Station to San Antonio, back to College Station and then back to Dallas. I would say that 100 miles of it was city driving. When I got back to the house I checked my average (reset it before I left) and it was 28.4. Taking into consideration that I have only owned the car for 3 weeks, I think thats pretty good cause I still have a pretty heavy foot These cars are amazing and I cant wait for the next road trip!!

 

2) Lower idling speed at stop lights. I think this is the biggie. If we could find a way to drop the idle from 700 rpm to 450, for instance, (without knocking out the main bearings) our overall gas mileage would go up considerably. Sitting with 5.7 cubic litres idling at 700 rpm is the big culprit to lower mileage.

A handheld tuner can change your idle speed. I think there is a used unlocked Predator on the forum now that can do it. Next question is how long would it take to make up the ~$200 for the used tuner?

 

I don't think the DIC uses Canadian gallon sizes on a Canadian car. It seems to convert fine to US gallons.

Peter

 

Our 98 MN6 with B&B cat back only got 34.6 from Corpus Christi to Houston. No elevation change.
My 97 A4 got 32.4 from Nacadoches to Houston. Appx 40 ft decrease in total elevation.
I love these cars.....

 

Only way to know for sure is for folks to post up their L/100KM readings. Those are guaranteed to be the same on both cars.

 

Well my Canadian car just showed me 10.8 l/100km and 21.6mpg when I check the display. If I convert 10.8 l/100km to US mpg I get 21.8mpg. Close enough to convince me that my car uses US gallons in the math.

Peter

 

Your car is definitely converting based on US gallons. For a car to get 35 MPG based on US gallons it would have to read 6.7 L/100 KM. I salute whoever gets that on extended highway trips. Best I've seen on my car even when taking it easy in 6th gear is 7.5.

 

do you have the 2.73 rear because that rear really racks up the good gas mileage