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donandmax

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I drove 100 mi. and only got 19.5 mpg, no codes, Colorfado country, no mountain driving but a couple of easy grades 60-70 mph. shouldnt I be doing better than that ?

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If you were on fairly level ground...I would think that the 98 Deville would get a good bit more that that.

My 2006 gets a slight bit better than that... and the older ones were well known for getting better mileage then the newer ones.

But 100 miles is barely enough to check it... a small varience on filling up, with that small of an amount of fuel will make a large difference in calculating it.

I am assuming you did the mileage calculating by hand.

If you used the DIC... when you reset it... your acceleration from the service road onto a freeway, and other minor things... would again affect it more on a short trip than a longer one.

This is a short trip I took down to my nephews wedding the other day.

Notice my "AVERAGE" speed ... that also included three pit stops and a 10 minute traffic jam on INterstate 20.

That pulled the average speed down a good bit.

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If you were on fairly level ground...I would think that the 98 Deville would get a good bit more that that.

My 2006 gets a slight bit better than that... and the older ones were well known for getting better mileage then the newer ones.

But 100 miles is barely enough to check it... a small varience on filling up, with that small of an amount of fuel will make a large difference in calculating it.

I am assuming you did the mileage calculating by hand.

If you used the DIC... when you reset it... your acceleration from the service road onto a freeway, and other minor things... would again affect it more on a short trip than a longer one.

This is a short trip I took down to my nephews wedding the other day.

Notice my "AVERAGE" speed ... that also included three pit stops and a 10 minute traffic jam on INterstate 20.

That pulled the average speed down a good bit.

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20120325_203236.jpg

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20120325_203252.jpg

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20120325_203344.jpg

Yes I used the DIC and reset the trip odometer
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Flat level highway driving should give you 25 -26 MPG. However, if you are looking at your "average" and it was low from city driving, it may take more than 100 miles to bring up the average. If you zeroed it out before the trip, you'd see 25-26.

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I drove 100 mi. and only got 19.5 mpg, no codes, Colorfado country, no mountain driving but a couple of easy grades 60-70 mph. shouldnt I be doing better than that ?

How did you calculate that mileage? Did you reset average mileage right before the 100 mile trip?

Oops, Ranger actually said that before me.

The saddest thing in life is wasted talent

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I drove 100 mi. and only got 19.5 mpg, no codes, Colorfado country, no mountain driving but a couple of easy grades 60-70 mph. shouldnt I be doing better than that ?

How did you calculate that mileage? Did you reset average mileage right before the 100 mile trip?

Oops, Ranger actually said that before me.

I filled the tank reset trip odometer and drove 100 miles round trip from one city to the next a couple of red lights some grades. Going up the grades it showed on the instant portion 5-6 mpg going down hill it showed up to 70 mpg overall avg for the trip 19.5. Thats all I know guys and thats why Im asking if these grades make that much differernce and all was level would my average would be much better. Everything runs normal including the a/c/ By the way the a/c was on all the way outside temp was 83 deg.
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I filled the tank reset trip odometer and drove 100 miles round trip from one city to the next a couple of red lights some grades. Going up the grades it showed on the instant portion 5-6 mpg going down hill it showed up to 70 mpg overall avg for the trip 19.5. Thats all I know guys and thats why Im asking if these grades make that much differernce and all was level would my average would be much better. Everything runs normal including the a/c/ By the way the a/c was on all the way outside temp was 83 deg.

In my "OPINION"... Yes... it should have been a little better than that.

That being said, The grades would have a big effect on the mileage, especially if the cruise was on.

I know each car is different, but on "MY" car... in hilly country, I actually get better mileage if I "DON'T" use the cruise.

I keep the "INSTANT AVG" on all the time.

As I start up a hill, I don't give it quite as much gas as the cruise would... slowly letting the speed drop off by 2 or 3 mph... and the "INSTANT AVG" will not usually drop below about 12 or 13... instead of 6 or 7.

Then I make up for speed loss going down the other side. :)

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I filled the tank reset trip odometer and drove 100 miles round trip from one city to the next a couple of red lights some grades. Going up the grades it showed on the instant portion 5-6 mpg going down hill it showed up to 70 mpg overall avg for the trip 19.5. Thats all I know guys and thats why Im asking if these grades make that much differernce and all was level would my average would be much better. Everything runs normal including the a/c/ By the way the a/c was on all the way outside temp was 83 deg.

In my "OPINION"... Yes... it should have been a little better than that.

That being said, The grades would have a big effect on the mileage, especially if the cruise was on.

I know each car is different, but on "MY" car... in hilly country, I actually get better mileage if I "DON'T" use the cruise.

I keep the "INSTANT AVG" on all the time.

As I start up a hill, I don't give it quite as much gas as the cruise would... slowly letting the speed drop off by 2 or 3 mph... and the "INSTANT AVG" will not usually drop below about 12 or 13... instead of 6 or 7.

Then I make up for speed loss going down the other side. :)

Yes I was using cruise the whole way.
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Hey Texas Jim I do that stunt too, sometimes. Mostly I cant stand to let someone behind me catch up so I stop and what the heck if I wanted the mileage I would have bought an econobox. I have even tried doing it with the ac off, I suppose to impress myself with the awesome mileage capabilities of these cars. Never made me feel as good as the tires spinning though. I did get 28 on a 40 mile trip hiway only, flat ground, ac off, reset once on the hiway.

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Hey Texas Jim I do that stunt too, sometimes. Mostly I cant stand to let someone behind me catch up so I stop and what the heck if I wanted the mileage I would have bought an econobox. I have even tried doing it with the ac off, I suppose to impress myself with the awesome mileage capabilities of these cars. Never made me feel as good as the tires spinning though. I did get 28 on a 40 mile trip hiway only, flat ground, ac off, reset once on the hiway.

I usually don't worry about mileage too much...

This was the other day when I was going to meet Bruce at the "Chevy Ride and Drive" event and then go to the Nascar race... :):)

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Speaking of which I meant to get Texas Jim in the STS-V that day, but by the time we got started with the event it was straight through to night.

Back to the original question, it is impossible to comment on whether that mpg is good on that route without more info on the route. If you measure your Cadillac on flat ground over a distance what mpg does it get?

The single largest influence on MPG is the driver, followed by speed, and then issues such as tune of the Cadillac and maintenance. My V seems to be running better MPG after I added the Corsa exhaust, but I have not had it on a LONG road drip to get better figures. On the way to the race it got over 22.5 mpg point to point.

Bruce

2023 Cadillac CT4-V Blackwing

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......and alignment, tires pressure, winds (either tail or head), etc.

Chuck

'19 CT6, '04 Bravada........but still lusting for that '69 Z-28

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I have come to the conclusion that Colorado is not the ideal place to test gas mileage. Reason: 5000-11000 ft altitudes. Hardly any flat roads without some sort of hills or grades If I went on a trip east of where I live I woulld have Vail Pass (10,000 ft) a few miles east, Eisenhower/Johnson Tunnel (11,000 ft) yesterday my average climbed to 20 mpg. I'll have to wait until I go back to Kansas to test that. But then again I will probably take the motorhome @ 8 mpg. So I guess 20 mpg aint that bad when you consider. Anyhow guys 20 sounds better than 8. Thanks for your replys

Don

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Folks, a 100 mile or a 1,000 trip is not going to yield accurate, reliable long term average MPG in the real world.

For thirteen years of ownership (4,871 days), I recorded every drop of fluid and every dollar put into my dearly departed 1998 STS and let Excel do the math. I used the GAL FUEL USED display on the DIC and reset that display every time I filled the tank.

Average MPG for 206,xxx miles = 21.6

Maximum MPG for 206,xxx miles = 27.02

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Well, I reckon we all have different needs and wants as far as knowing the avg mileage.

I know that your way is the best and "BY FAR" the most accurate... but...

I, personally, don't have the discipline to do what you do with Excel.... I sometimes wish I did.

Over the last 6.5 years and 143,000 miles on the two 2006 DTS's that I have had...when I am out on the highway and running at a reasonable speed...(for me)... I consistently get 21.5 to 22.5 MPG...

This is figured with a calculator and based on the gallons I actually put in the tank and the actual miles driven since the last fillup.

I have did this pretty regular since I bought the first DTS.

Occasionally, if I have been running really easy... it is just a tad better... if I am running hard, it is usually a little worse.

Running around town... which for me is mostly freeway... I get 18 to 20 mpg.

Doing it by hand it usually comes out real close to what the DIC says.

That's close enough for me... :):)

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I have a 97 Deville. I average in town drving around 20. When I drive in on a few 40-50 mile trips my average will go to 23-24. You can check to make sure you intake bolts are tight. Also check to see if you plug wires are arcing on the new metal fuel rail put in after the recall. I had trouble and had to put looms on the plug wires.

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