EPA Testing Procedures

[Shortie771]

While reading an incredible long article (more like a book) I came across a page that has some interesting information where EPA numbers come from and figured I would share it here.

Car Bibles : The Fuel and Engine

According to this, we should all feel much better about our % over EPA numbers. Especially if you own a vehicle build before 2008 because our true EPA numbers should be much lower then they are, once all factors are considered. So my REAL EPA (due to inaccurate testing) should be closer to 24.4mpg combined, instead of 28mpg. If this is true then the 41.6% over EPA I got on my last tank (personal best btw) would actually be 54.6% over EPA if adjusted to today's EPA standards.

EPA TESTING PROCEDURES
Congress and car company lobbyists required the EPA to measure mpg figures using the following simulated real world conditions in a lab. That's right - EPA testing happens on a dyno in a lab, not on the open road.
Average highway speed : 49mph
Maximum highway speed : 60mph
Temperature : 75°F
No rapid acceleration
No air conditioning
No passengers
No rough roads
No hills
No wind
No low tyre pressures
No ethanol in gas

The first problem is the last point : no ethanol in gas. In America, it's almost impossible to buy zero-ethanol petrol - it's all E-10 (see E10 elsewhere) so you're already going to be down 5% on the EPA figures even if you could meet all the other requirements.

I also learned that the EPA ratings for European cars are higher (probably due to US NOx standards) meaning if you own a European car you probably won't get as much over EPA (if you do, you're awesome!) as you would with the same car in the US. The bar is already set higher, leaving less room for improvement.

[Hersbird]

Except they arbitrarily just reduce the actual test results a certain percentage to take those things into account. They also add stop and go to the highway test. (I don't stop on the highway until it's time to get gas or pee). See I'm the other way around, I want a real, long distance, highway steady state MPG test. Basically what a car or truck gets at a constant 65mph. Hills may hurt on the way up but they sure are nice on the way down. Technically they can actually help by basically be a forced pulse and glide.
Overall the rating is good, many people get worse MPG but the few here show they could actually beat the numbers with some thought and attention. They do need to fix the manual transmission forced high rpm shifting penalty. If you want to be the cool guy beating the EPA rating by the most get a manual because they make the testers drive like a moron with the shift points.

[oldtamiyaphile]

You only need to look at my sig to see how wildly variable EPA/NEDC numbers can be, same driver, different cars, almost a 100% spread

[oil pan 4]

Isn't their highway testing speed kind of unrealistic too?

[Shortie771]

Originally Posted by oil pan 4

Isn't their highway testing speed kind of unrealistic too?

Completely unrealistic! Most highway speeds around me are 75mph. Heck, the back road I live off of has a speed limit of 60mph.

[TimV]

Originally Posted by Shortie771

I also learned that the EPA ratings for European cars are higher (probably due to US NOx standards) meaning if you own a European car you probably won't get as much over EPA (if you do, you're awesome!) as you would with the same car in the US. The bar is already set higher, leaving less room for improvement.

So does this mean that i aim awesome

[Shortie771]

Originally Posted by TimV

So does this mean that i aim awesome

Precisely! Way to go