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The Pontiac Vibe, which weighs 850 lbs more than an Elise, and (I'm guessing here) must be less aerodynamic, is rated 25 city and 32 highway with "our" engine and a six speed. The Elise is rated at 23 and 27. I was always under the impression that the EPA test cycle is a controlled run on a dyno with pre-set rates of acceleration to certain speeds, then steady cruising at that speed for a precise time, then slowing, etc etc. They then factor the weight and aero drag to come up with the numbers we see on the window sticker. If this true then how in The Name of Colin Chapman can the Elise be rated so low? If it isn't, does anyone here know the actual test proceedure? The Elise test is obviously badly flawed based on both common sense and the real world mileage I am getting.

Richard Fogg
 

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My guess is that in the quest for a little more power and tourque gas mileage went out the window, plus the final drive ratio is probably a bit lower. That being said, I think people will see 30mpg plus in real world driving on the highway.

Tboy.
 

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Does anyone know what the 111R is rated at elsewhere in the universe ?
Once mine is run in, I hope to keep it below 20mpg :D
 

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arefog said:
...I was always under the impression that the EPA test cycle is a controlled run on a dyno with pre-set rates of acceleration to certain speeds, then steady cruising at that speed for a precise time, then slowing, etc etc. They then factor the weight and aero drag to come up with the numbers we see on the window sticker...

Richard Fogg
yes. except i think the weight is already factored in by running the car on the dyno which simulates all the weight-related road-loads through its configurable flywheels.

i am also puzzled as to the epa rating. even worse, i actually keep seeing different numbers used by different sources too. the first estimates that all the publications put out were more like what i was expecting.

i don't remember what the test specification is on shifting. maybe that's a factor. but still.
 

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Re: Re: Riddle me this.....EPA

masheen said:
I don't remember what the test specification is on shifting. maybe that's a factor. but still.
I had an RX-7 with a "shift" light. I was told that, if there was an upshift indicator, the EPA testers had to shift up when that indicator light came on. Maybe the EPA testers thought the Elise shift light meant the same thing and were shifting at redline! :)
 

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The elise has a high Cof D for the day...mid to high 0.3.
The relative lack of weight and luckily, the gearing, help in achieving reasonable mileage in mixed driving.
m
 

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>>>The elise has a high Cof D for the day...mid to high 0.3. The relative lack of weight and luckily, the gearing, help in achieving reasonable mileage in mixed driving. <<<

* Cd is not enough to go on. The air drag a car experiences is related to the Coef. of Drag as well as the frontal area. That is two cars with the same Cd don't experience the same drag force if their respecive frontal areas vary.

* The Elise Cd is supposedly around 0.35-0.36 with the soft top on. It's claimed to be a bit better with the hard top - but I have never read a number for it. The car would also have less Cd with lower front fenders, less of a coke bottle shape. And a cover over the sail panel area depression over the motor.

* The EPA tests use fudge factors to try to correct the dyno test to real world results. But the factors are more useful for larger, heavier cars.

* You can easily beat the EPA results on the Elise. It is economical with fuel.
 

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EPA

I have read the other manufacturers understand how the EPA does their testing. And uses that info to meet the CAFE standards.

What is really funny is hearing that someone buys an SUV and gets only 50% of the sticker mileage.

I my Miata (last tank) the mileage was about 17. Top down - timing advanced 18 degrees and I am either on the gas or the brakes. Little freeway driving. I am not too concerned as I fill up once every other week.

It would also be nice for the pollution standards be set by volume and not just by the quantity. A 10 liter engine will pollute a lot more than a 2.2 liter engine. What can I say other than our politicians are the best money can buy.

have fun

Nick
 
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