How do they test MPG on cars?

How many Rpm's do they use is really the question. Thanks.

Relevance
• 8 years ago

They put one gallon of gas in the car and drive until it stalled. Count the miles it travels. That's basic method.

• Anonymous
8 years ago

MPG is an acronym for how many miles can your car go on a tankful of gas. MPG =

"miles per gallon fuel." We say miles per gallon because different cars have different gas tank volumes. And, tankful distance is not usually important to MPG - except to determine what each gallon of fuel averages out to. That becomes MPG.

I figure the answer at fillups - while the nozzle is filling the tank, like this.

I notice my car was driven 250 miles since the last tank fillup. Today, after a few clicks on the filler hose handle, to make sure no more gas would go in, the gas pump showed I added 10 gallons of gas. You make a division mark on a piece of paper, and you put 10 on the left side of the leg, and 250 inside to divide 10 into 250 - or what ever those two numbers are for that fillup. 10 goes into 250, 25 times. That shows my car goes 25 miles distance on each gallon of gas. Got that math?

RPM's means, how many times the motor makes one revolution - at any given steady speed. RPM = revolutions per minute. Minute really means, at a given steady speed.

There are several ways of reading or determining rpm. That data is transferred to a gauge where the RPM numbers are shown. My car dash has such a gauge. Its a needle that rises to markings from 0 to 6000. Meaning 6000 RPM's. Race cars have 15,000 as their top. At idle, my gauge stops at 700. Going 70 miles per hour, the gauge - called a tachometer, has its needle at 2,200. A speedometer shows speed at any given time.

Now, being in many cars as a mechanic, and owning cars and trucks, I notice that some cars show 2000 rpm at 70 mph, some 1,800 - my car, 2200. The lower the number means that car is much more efficient on fuel that a car showing the higher numbers. Wow! That is a significant bit of knowledge - if I want to check the efficiency's of two cars - like when buying them! And that was important to me.

I'm a guy who knows unseen friction drag - it increases with wear, and requires more fuel to operate pistons and gears in. And, also unseen dirty pistons, valves, and gears, they lower combustion efficiency, and proper shifts. So, I found a brand of additives that removes, or lowers friction, and also cleans the motor and transmission with-out-harm. This brands advantages - the Mega Power Brand, ups power and ups fuel economy - or restores the like new power and fuel economy by cutting friction to the lowest levels, and by cleaning safely where oil can't. That product seems good for my way of thinking and my cars and budget.

That's the skinny on knowing what MPG and RPM, and what takes away and what can restore both means? Clear as mud, I bet! Hey! tuck it away. You may need that info on those taxi cab shows, or, who wants to be a.... show. You never know! Hopes this helps.

• 8 years ago

Fuel economy is measured under controlled conditions in a laboratory using a standardized test procedure specified by federal law. Manufacturers test their own vehicles—usually pre-production prototypes—and report the results to EPA. EPA reviews the results and confirms about 10-15 percent of them through their own tests at the National Vehicles and Fuel Emissions Laboratory.

In the laboratory, the vehicle's drive wheels are placed on a machine called a dynamometer (rollers) that simulates the driving environment—much like an exercise bike simulates cycling.

The energy required to move the rollers can be adjusted to account for wind resistance and the vehicle's weight

On the dynamometer, a professional driver runs the vehicle through a standardized driving routine, or schedule, which simulates “typical” trips in the city or on the highway.