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1987 GLHS Window Sticker MPG @ What MPH?

1K views 16 replies 6 participants last post by  detobias 
#1 ·
I just took my GLHS on a 150 mile drive and at 70mph the engine is turning about 2,800 rpms. I have not filled it back up to verify MPG, but because of the RPMs at 70mph it got me thinking about the window sticker MPGs. The window sticker for an 87 GLHS says 20 city and 29 hwy, but I assume that was at like 65 mph or what ever the national speed limit was back then, so 70 today will be a bit less MPGs.

Does anyone remember what speed they used for the MPGs on window stickers back in 87?
 
#3 ·
I get that they were rated based off lab results, but it would have been done at a given speed otherwise they could have tested them at idle and claimed hwy mileage. Just like the same engine combo could have had better MPG when the national speed limit was only 55.

I am guessing the lab turned them at what ever rpms 65 mph was.
 
#5 ·
"EPA tests vehicles by running them through a series of driving routines, also called cycles or schedules, that specify vehicle speed for each point in time during the laboratory tests"

Thanks
Randy

 
#6 ·
And as your post stated, prior to 2007 only city and hwy were used.

Again my question is what did they consider why back in 87?

To me city requires the variable speed testing and why should be at a constant rate hence better fuel economy.

But maybe I am wrong.
 
#7 ·
I may be wrong, but in 1987 the national speed limit was 55 MPH. I forget what the window sticker said about mileage for my 1986 GLHT, probably about the same as your GLHS. I bought my GLHT in March of '86. In July of '86 drove out to the Grand Canyon in Arizona and was getting mid 30s for MPG.
 
#9 ·
I was able to get 32mpg once.....just...once.
Dry sunny day.
Perfectly flat road for miles and miles.
Steady 65.
Barely touching the gas.
No passenger.
 
#11 ·
My 85 GLHT was rated at 19/29 MPG. Yes hwy. speed limit was 55 MPH when these cars were new. After intercooling car with Spearco kit in 1987, changing exhaust to mandrel bent 2.5", and MP logic module, car would consistently get 35-37 MPG driving to Great Lakes Dragway. I could drive from MPLS to dragstrip outside Kenosha, WI on ONE tank of fuel. that was around 390+ miles. Then dumped in the good stuff at the dragstrip.
Another time years later driving that same route going to a SDAC convention, a friend was driving a 85 bone stock SC T1. We had to stop for fuel because he was on fumes, I still had 1/3rd of tank left! He was getting like 26-27 MPG, while mine got 37 MPG.
I guess intercooling car made for a much more efficient air pump. The SC clearly had an advantage in aero vs. the GLHT. By that time though, the GLHT had lots of porting work done to top half of engine.
 
#12 ·
My 85 GLHT was rated at 19/29 MPG. Yes hwy. speed limit was 55 MPH when these cars were new. After intercooling car with Spearco kit in 1987, changing exhaust to mandrel bent 2.5", and MP logic module, car would consistently get 35-37 MPG driving to Great Lakes Dragway. I could drive from MPLS to dragstrip outside Kenosha, WI on ONE tank of fuel. that was around 390+ miles. Then dumped in the good stuff at the dragstrip.
Another time years later driving that same route going to a SDAC convention, a friend was driving a 85 bone stock SC T1. We had to stop for fuel because he was on fumes, I still had 1/3rd of tank left! He was getting like 26-27 MPG, while mine got 37 MPG.
I guess intercooling car made for a much more efficient air pump. The SC clearly had an advantage in aero vs. the GLHT. By that time though, the GLHT had lots of porting work done to top half of engine.
I love it.
More mods plus more power = higher gas mileage.
 
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#13 ·
This thread reminds me of a situation between Oldsmobile and the EPA.

The EPA requires everyone to follow their edicts, however dumb.

Highway ratings had to be according to EPA driving cycles or schedules.

In the 1980's, FWD Olds Delta owners routinely reported fantastic mileage.

This was with the corporate Buick 3800 V6 Engine and highway driving.

The EPA discovered Olds had created a special, efficient cruise mode.

This cruise mode was within the Olds Delta 3800 electronics.

This mode activated when the Olds was cruising at a steady highway speed.

Once the EPA pinned down the special software they made Olds eliminate it.

From about 1991 on the big Olds achieved good mileage, down from great.

Thanks
Randy
 
#14 ·
One has to wonder what bonehead(s) would want something eliminated that achieved and outperformed the guidelines.
I'm guessing ego maybe?

My brother bought a new 1997 Chrysler Sebring Coupe with the V6 and my GLHS with a Stage 3 LM would consistently outperform his brand new car in emissions tests.
Gas mileage on mine was better also, but then, a 4-cyl. in a lighter car will do that.
 
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#15 ·
Typical of an unelected federal bureaucracy, they need total control at any cost.

Current cars have design features that dictate emissions over economy.

The cats must be kept hot at all times by any and all means, period.

Retarded ign. timing and overfuelling can accomplish that.

They allow no compromise or discussion.

Thanks
Randy
 
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