2011 Ford Mustang V6 rated 31 mpg highway

[Homeslice]

Well I'm not a physics major, but if you take 2 engines with the same displacement but different HP, I don't see how more horsepower ALWAYS means less fuel economy UNLESS someone is actually taking advantage of it by accelerating harder. And I doubt the EPA test is doing that, does it?

Personally I think the increased weight of today's vehicles is more to blame.

[z06boy]

Originally Posted by Homeslice

Personally I think the increased weight of today's vehicles is more to blame.

That too in some cases for sure. I'm pretty sure that my 1992 Mustang LX 5.0 was lighter than the new Mustang. I did not look it up before posting this so I may be wrong and get slammed for saying it.

[pdog]

Cars today are also significantly heavier. My 89 CRX was 2200 lbs I think and the original Miata was around that too. These days you'd struggle to find a car under 3000 lbs.

[Adeptus_Minor]

Originally Posted by z06boy

That too in some cases for sure. I'm pretty sure that my 1992 Mustang LX 5.0 was lighter than the new Mustang.

By about 500 lbs, actually, according to Edmunds.

[z06boy]

Originally Posted by Adeptus_Minor

By about 500 lbs, actually, according to Edmunds.

Sounds about right but I wasn't sure...thanks.


As far as the CRX mentioned...I'm pretty sure they were even less than 2200 lbs. I think one of my 4 that I owned was around 1800-1900 lbs...fun little car.

[goof2]

Originally Posted by Homeslice

Well I'm not a physics major, but if you take 2 engines with the same displacement but different HP, I don't see how more horsepower ALWAYS means less fuel economy UNLESS someone is actually taking advantage of it by accelerating harder. And I doubt the EPA test is doing that, does it?

Personally I think the increased weight of today's vehicles is more to blame.

At its most basic more power from the same displacement requires more fuel and more air. When it gets more complex that trade off may no longer exist. One example is using aluminum for the block and heads vs. iron, better electronic controls, and requiring premium fuel allows a higher compression ratio in an engine before knocking occurs. That engine will create more power without increasing fuel requirements. It doesn't always mean anything, but it still stands as a good general guideline.

Increased weight is certainly a factor in lowering mileage, while increasingly more complex gearboxes help raise economy. There are a lot of things that will change mileage.

[MILK]

2010 Camaro 29 mpg

[Dave]

Originally Posted by goof2

Two things happened. First the EPA changed the way they rate fuel economy in order to make them closer to real world driving conditions. Look at fueleconomy.gov and see if the cars rated 30mpg+ city 20 years ago aren't given significantly lower numbers now.

Second, the cars today are much more powerful. This is a base Mustang. The most powerful factory Mustang in 1990 (the 5.0) made 225hp. In 1990 you couldn't get 300hp+ in a standard engined Corvette or Porsche 911. The Ferrari 348 came with an even 300hp. Power isn't free.

on a turbo its practically free

[goof2]

Originally Posted by Dave

on a turbo its practically free

Not if you actually use the turbo. More air (what a turbo does) requires more fuel. There is no getting around that. One of the car magazines did a super group comparison test issue where they had 3 sets of group tests. To give you an idea of the cars involved the top group included a BMW M5 (V8), the mid group had an M3 (V6) and the bottom group had a Neon SRT-4. The worst observed mileage they recorded out of all the cars (7 or 8 total) was from the 2.4 liter turbo Neon.

Turbo cars do well in the EPA's test cycle because it doesn't require using the turbo much. When driven hard they don't do as well.

[Rider]

Damn good mileage. I'm partial to GM but with numbers like that...... I could be lured into buying one.