EPA - Cars LESS Fuel Efficient Than In The 80s!

[Areometer]

Detroit - With Congress poised for a final vote on the energy bill, the Environmental Protection Agency made an 11th-hour decision Tuesday to delay the planned release of an annual report on fuel economy.

But a copy of the report, embargoed for publication Wednesday, was sent to The New York Times by a member of the E.P.A. communications staff just minutes before the decision was made to delay it until next week. The contents of the report show that loopholes in American fuel economy regulations have allowed automakers to produce cars and trucks that are significantly less fuel-efficient, on average, than they were in the late 1980's.

>> Read more @ TruthOut.org

[Hornhonker]

The EPA has released its fuel economy numbers for 2005 vehicles (although it appears that the release was delayed until after the energy bill passed, proving that Washington can make a political issue out of simple math). Industry-wide, fuel economy increased 0.2 MPG from last year to 21 MPG. Go team! Oh, but that’s still 1.4 MPG less than the peak reached in 1987, a year in which carburetors were still standard equipment on some vehicles and vehicle styling was still inspired more by rectangular masonry objects than small candy confections. Honda topped the rankings with an average of 25.1 MPG, while Toyota came in a distant second 23.5 MPG. Ford had the worst average of any company in the report at 19.5 MPG.

From autoblog.com

[GreenLady]

I saw that same statistic announced on ABC news. They just left it hanging out there without comment or any kind of in-depth report as to why fuel economy is so abysmal today. At first I was a little shocked but after I thought about my coworker's constant complaints about the horrid gas mileage for her Jeep, I wasn't really that surprised after all.

(She pays $400 a month for gas. I pay $100 a month for gas. We take the same route and drive the same distance (give or take 5 miles) to work. Oh yeah, I drive a 15 year old Camry. I expect my numbers to improve when I get my Prius.)

[8AA]

Back in the 70s, I used to own a 2-cylinder Honda microcar (600 Coupe). It had terrible acceleration, but I could get about 50 mpg on the highway. Now I drive a Prius which has much better acceleration, and I typically get highway mileage in the low 50s with the A/C running.

There have been great improvements in automotive technology, unfortunately most US car buyers are more obsessed with power than economy. So who is really to blame, the US car manufacturers who are building the types of cars people want to buy, or the consumers with their "go fast" mentality?

[Tideland Prius]

Well, just as we've been improving engine performance and efficiency as well as using light weight materials, our cars have been loaded with safety features and extra insulation. Not to mention the sudden desire to own a truck. That has basically cancelled out the economy gains.

airbags themselves have sensors and a computer to control their deployment. Then there's sensors for ABS, VSC, TCS, sensors for side airbags, gyro for GPS, wheel sensor for GPS, the GPS unit itself, moonroofs, more side impact beams, more nuts and bolts (Lexus carves out a bit from the screw head resulting in a 9kg reduction in weight).

[acdii]

There is a real reason that fuel economy is lower now than in the 80's, the carburetor. It cannot meet any CARB or other emissions standards, all cars are now fuel injected. If you look at some of the older cars that had carbs, they were easily getting 30 MPG or more. Emissions standards are so high that fuel management systems and related parts have killed fuel economy. Another factor to consider is you can only get so much out of a drop of gasoline. To get the proper burn for complete combustion, the air to fuel ration must be 17:1, no higher, no lower. If you lean it down, you get beyond the 17:1 ratio, emissions go up. Carbs could easily get it above 17:1, run a lean burn carb and you get very good fuel economy, your emissions suck, but great gas mileage.

[priusenvy]

Originally Posted by acdii

There is a real reason that fuel economy is lower now than in the 80's, the carburetor.

You're so hopelessly misinformed it's scary. Other than cost and simplicity, carburetion has no advantages over fuel injection. Ignoring all of the efficiency and emissions advantages of FI, there's still the obvious advantage of being able to run much higher compression ratios with FI compared to carburetion.

The reason avg. fuel economy is lower now compared to the 80s is that cars now are heavier and much more powerful. Back in the '80s 0-60 in under 10 seconds was considered adequate. Today only the very slowest cars can't break 10 seconds 0-60.

The only emission standard that is having a significant impact on fuel economy is SULEV, specifically by requiring movement of catalytic converters closer to the exhaust manifold and affecting exhaust flow (recent tech column question in R&T pretty much asked this exact question).

[dr_d12]

The car manufacturers are responding to consumers. They're producing the one thing that the consumer is willing to pay more for: horsepower.

[drees]

Originally Posted by acdii

To get the proper burn for complete combustion, the air to fuel ration must be 17:1, no higher, no lower. If you lean it down, you get beyond the 17:1 ratio, emissions go up. Carbs could easily get it above 17:1, run a lean burn carb and you get very good fuel economy, your emissions suck, but great gas mileage.

Originally Posted by priusenvy

You're so hopelessly misinformed it's scary. Other than cost and simplicity, carburetion has no advantages over fuel injection. Ignoring all of the efficiency and emissions advantages of FI, there's still the obvious advantage of being able to run much higher compression ratios with FI compared to carburetion.

The only emission standard that is having a significant impact on fuel economy is SULEV, specifically by requiring movement of catalytic converters closer to the exhaust manifold and affecting exhaust flow (recent tech column question in R&T pretty much asked this exact question).

Sorry, you're both wrong. :P

Carburetors have a couple big disadvantages compared to fuel injection.

1. Carbs are much more restrictive than fuel injection setup, which limits horsepower, this requiring a larger engine. A larger, less restrictive carb, will not atomize/mix the air/fuel as well leading to higher emissions at low air flow rates.

2. Carbs have very poor control over the amount of fuel mixed with the air compared to fuel injection systems, which accurately measure air flowing in to the engine, adjust fuel injector duty cycles as appropriate for conditions and then also adjust the ratio further based on feedback from oxygen sensors in the exhaust. Modern FI systems keep track of how it's had to historically adjust FI duty cycle to meet the targeted air/fuel ratios so that it hits the desired air/fuel ratio targets with even more accuracy.

The only reason you can run more compression with FI than with a carb is because a FI system is so much better at controlling the air/fuel mixture as well as being able to produce a very evenly mixed air/fuel mixture. If you're not able to control the air/fuel mixture or if you have pockets of mixture with high or low amounts of fuel, the tendency to detonate/ping goes up a significant amount which will eventually lead to engine damage depending on how bad it is.

The air/fuel ratio that (almost) all cars run at today under normal operating conditions is approximately 14.7/1 (stoich), not 17/1.

The reason that cars run at stoich is because it is the leanest air/fuel ratio that burns cleanly. If you lean the air/fuel ratio out more than that, power will go down slightly, but NOx emissions (the stuff that leads to smog) skyrocket.

Not to mention that running lean can also cause your catalytic converter to overheat reducing it's lifespan.

The Honda Insight was able to run air/fuel mixtures leaner than stoich because it has a special, very expensive catalytic converter which traps NOx emissions and then would burn them off when the car ran rich for a little bit.

Because diesels don't use a throttle body and regulate power output by varying the amount of fuel injected, they also run a wide range of air/fuel mixtures, but this is also why diesels have only recently been cleaned up enough to meet federal emissions standards by being fitted with either a NOx trap (like the Insight) or Urea injection. Commonly, a reduction in compression ratio is also used to help reduce NOx emissions, but of course, this reduces fuel economy a side-effect.

So yes, modern emissions requirements have definitely caused cars to burn more fuel than they would otherwise. I would fully expect that you could get another 10-20% fuel economy out of a car that did not have emissions requirements to worry about with just ECU tuning.

Also, modern catalytic converters flow so well that they do not provide for much of a restriction under most loads, even when they are closely coupled to the exhaust ports to encourage quick warmup. In fact, if you completely removed them, you would not see a significant increase in fuel economy, may a couple percent at the most. You might see an increase in peak power output, but that's it.

Sorry for the long reply, but it's a pet peeve of mine when someone berates someone for misinformation when the information they provide is not much better.

[priusenvy]

I stand by my statement that the reduction in fuel economy compared to the '80s is due to cars being heavier and more powerful. Also, my statement that current emission standards are not significantly impacting fuel economy is partially based on the following correspondence which appeared in a recent issue of R&T.

Emissions Philosophy 101

Was there a year, perhaps in the late 1990s or early in the 21st century, when the emissions controls were made restrictive enough so as to significantly impact performance and fuel consumption?
L. David Egan
Livonia, Michigan
We'd say that year was 1972. That's when compression ratios plunged to kill oxides of nitrogen, and carburetors were asked to do the work of electronic fuel injection with no more help than several miles of vacuum hose. Power disappeared along with driveability; it was the automotive Dark Ages.
By the mid-1980s emissions controls had caught up to the regulations — barely — with the advent of electronic fuel injection. Today, the precision of fuel injection — which was developed strictly for emissions compliance — along with decades of attention to the details of the combustion process, airflow improvements, better materials and manufacturing, etc., allow for unprecedented power and the lowest emissions ever. Call it the Renaissance.
If there is a retrograde performance step in favor of emissions in the modern era, it likely started a few years ago when SULEV (Super Ultra Low Emission Vehicle) standards were met by many cars. The main issue with gasoline SULEVs is they place a catalytic converter so close to the cylinder head there is less room for favorable exhaust manifolding. Power drops about 10 percent but the emissions are so nearly nonexistent that under the worst atmospheric conditions SULEVs actually emit cleaner air than they ingest.
The future would seem an Enlightenment. Attention to the fundamentals of combustion through hard-won knowledge and the power of computer modeling hold much promise, as do emerging, non-combustion technologies. But when considering strictly gasoline-burning engines, the low fruit has been picked, and increasingly stringent emissions controls may well demand some power and efficiency sacrifices.
Still, in the end, with the exception of transitional periods, emissions regulations must be judged as having improved performance and economy because they have forced attention on combustion fundamentals and made economical the technologies to service those fundamentals.