Explain to me: MPG ratings

[Initech]

So I'm looking over Consumer Reports' reviews at various cars and I happen to come across this bit of information that is seriously making me reconsider a hybrid purchase:

Green car Toyota Prius
The fuel-stingy, gas/electric Prius hybrid ($23,000) provides reasonable performance in addition to excellent fuel economy. Its 44 mpg overall is the best we’ve measured in any five-passenger vehicle. The interior is roomy enough to make it a viable alternative to a family sedan. A good alternative is the 37-mpg Honda Civic Hybrid.

http://www.consumerreports.org/cro/cars/new-cars/top-picks-for-2007-4-07/overview/0704_top-picks-2007.htm

Now... the sticker rating on the Prius rates it as being between 51 and 60 MPG, while the sticker rating on the Civic Hybrid rates it as being between 49 and 51 MPG. Now why are these ratings different than what the car actually gets? Are these numbers artificially inflated or what is the deal here?

If the Civic Hybrid only gets 37MPG, while most of the cars I'm looking at average 30MPG at the most, that's not really much of a difference, right?

[Kutjara]

1. The "official" fuel efficiency ratings are pretty artificial.

Environmentalists have been attacking them for a number of years, because the various types of driving the cars undergo when being tested bear little resemblance to real-world driving. The Consumer Reports test probably better reflects the real world. Also, hybrid cars need to be driven a little differently from regular cars to take full advantage of the electric motor (in brief, you have to drive more smoothly and plan manuvers ahead a bit more to avoid unnecessary acceleration and deceleration). These factors mean that it's likely that neither the official figures or the Consumer Reports ones reflect the cars' true fuel economy.

[Clovis Sangrail]

2. it's a pretty good difference

well.. at 30 mpg you'd only be getting 68% of the milage of the Prius.
or 81% of the milage of the Civic.
Depending on how much you drive this can add up to a fair amount of money every year.

The EPA stuff really seems to be only ballpark.
I have a 2002 prius and average between 43 - 45.
(I seem to get better milage on long highway trips than around town)

I know a person w/ a 2005 that averages around 48.

[blues90]

3. when I worked for ford

I spoke to a few engineers and their tests involved a car with one gallon of fuel in a attached glass jug , , one average passenger and unloaded car driven easy , once the fuel ran out this was the highest rating than they adjust this for the lowest rating by calculations i did not fully understand the math there .

[Initech]

5. That doesn't make a whole lot of sense.

They should just throw the jug across the hallway and see how far it goes. That would probably make more sense.

[Beaverhausen]

4. My 2005 Prius gets around 44-46, my co-worker has a 2006 and gets a lot more

...they do more highway driving.

Also, those non-hybrids rated at 30 MPG aren't getting that, either.

[Initech]

6. I need to look at the Prius again

When I first test drove it, I wasn't impressed with the control system at all, but considering it gets the best MPG of any of the cars I looked at, maybe I wrote it off too soon.

[Gabi Hayes]

7. FWIW, I have a Jetta diesel, and the mileage varies wildly, the most

crucial variable being outside temperature.

I've gotten as low as 30 mpg when it's below zero, and as much as 50+ on trips lasting over an hour. this is at about 60-65mph, with AC on. that's the best thing about it: AC doesn't affect mileage or load, even in mountainous territory. never had a car that didn't struggle with AC on in the mountains. usually had to turn it off when climbing. don't have to now.

it takes awhile to warm up, so it's not so good on short commutes. I'd say an hour drive each way is optimum. it also gets better mileage on the way home from work than in the morning. apparently the engine stays warm enough over that time to affect the mileage.

one of these days I'll call VW and see if there's something I can do about cold weather driving

I really like the car, though. comfortable, and very roomy. I'd say overall mileage, averaged out, is close to 40, 'cause I do a short commute, which is most of my driving. had I known what I know now, I probably would have gotten a Prius

[Initech]

8. I live in Southern California, cold weather driving usually isn't a problem

[tammywammy]

17. Have you tried using a fuel additive?

I use Powerservice Diesel Kleen

http://www.powerservice.com/dieselkleen_cetane.asp

Silver bottle is for summer, white bottle for winter.

I have a 2006 Beetle TDI. I loooove it. :loveya:

I drive 12 miles one way to work right now, and about 3 miles of it's on the side roads, the rest is highway. I get abour 42 mpg right now. :)

I prefer having the diesel to a hybrid. End in the I can run biodiesel in my vehicle, while a hybrid will always need some gasoline.

[bullwinkle428]

24. Get a block heater for your TDI! I've done lots of research

on them over the past couple of years, and have learned a fair amount even though I've yet to purchase one. I know several posters over at www.tdiclub.com use a block heater which allows them to plug it into a wall socket overnight keeping the oil and all other moving parts closer to operating temperature in cold weather. I think it's even more important as you mentioned most of your trips are short commutes.

[skids]

9. 2007 -- low forties in winter, low 50's currently.

Mix of about 2/3rds highway, 1/3rd country driving, A/C off. It's really a matter of how you drive though and what accessories are turned on. A friend of mine is not a very graceful driver and is still under 40 even with winter over.

My 2002 I had before this one got high 30's in the winter and low 40's in the summer.

Eventually I'll spring for a post-factory plugin kit, or upgrade if/when there's a stock car that has it, and drive laughing past many more gas stations than I do now, but for now I'm going to ride out the warranty.

Never believe sticker mileage. Always hit the public boards and looks for real world results. The hybrid manufacturers actually would prefer the tests weren't so off because it makes them look bad.

[Initech]

10. I don't. My dad's MDX was rated at 19 - 26MPG...

But looking at the trip computer yesterday, he actually averages around 15 - 17MPG. Yeah, just a little off!

[Wilderness Sportsman]

14. I'm waiting for a 4cyl hybrid pickup

I need just a touch more utility, although the Prius is a heck of a car.

The Corolla also gets great gas mileage for a non-hybrid, but I found it a touch not wide enough.

[Initech]

15. GM is supposed to be producing 30MPG hybrid trucks later this year

Yeah, I know they're a sponsor of the Big Fat Idiot, but this is a first. They have a hybrid GMC Silverado and a hybrid Chevy S10 in the works.

[joshcryer]

11. Just a random comment, I was getting 55PMG in town with my motorcycle.

I miss that thing, but now I'm using public transport so it ain't half bad.

[ReadTomPaine]

12. MPG standards are fairly complex and have just recently changed to a more stringent formula...

Here's a good description from Wiki:

... the Environmental Protection Agency (EPA) is the government body that makes the calculations that auto manufacturers use when advertising their vehicles. Separate numbers are given for city and highway driving<4>. The EPA tests used through 2007 do not directly measure fuel consumption, but rather calculate the amount of fuel used by measuring emissions from the tailpipe based on a formula created in 1972. The cars are not actually driven around a course, but are cycled through specific profiles of starts, stops, and runs on a chassis dynamometer in a laboratory environment. As emissions standards have become more strict due to smog, most of the resulting numbers do not directly correspond to what people actually experience when driving. Most often, the EPA estimate of mileage is several percent higher than what the average driver manages to achieve in practice, although there are some cases where the difference is nearly 200% higher than what the average driver achieves.

Due to concerns over the accuracy of this method, additional tests were devised and used for years but were not counted as part of the final EPA MPG number. They were approved in 2006 for use beginning with model year 2008 vehicles<5>. The new tests are additional to the original tests and more closely reflect the average American's driving habits of rapid acceleration and fast highway speeds. They also make use of the AC and test the car in cold conditions. The fuel economy ratings for vehicles tested under the new system are expected to drop an average of 12 percent on 'city' mileage, and 8 percent on 'highway' mileage. However, fuel usage is still measured by carbon in the car's exhaust.

The old test method was particularly favorable to hybrid cars, as the driving style used low speeds (highway speeds of only 45mph) and mild acceleration where a hybrid can turn the gas engine off. AC usage negatively impacts a hybrid's mileage, especially during idle, and cold weather can prevent a hybrid from turning the gas engine off because of the catalytic converter cooling to below optimal filtering temperature. As such, these vehicles may see the largest decrease in fuel economy ratings – city economy is expected to drop by 20 to 30 percent, and highway economy by 10 to 20 percent.

However, this new rating will not in any way affect the Corporate Average Fuel Economy (CAFE) rating for a company. This standard is mandated and controlled by the Department of Transportation, and not the EPA; the fuel economy ratings used to calculate a manufacturer's CAFE score is not the test utilized by the EPA to produce the ratings displayed on the window sticker.

http://en.wikipedia.org/wiki/Fuel_economy#Measurement_cycles

[musiclawyer]

13. My 2002 Hyundai Santa Fe 4x4 gets 24 mpg

highway driving, which I mostly do. Pretty much as advertised. But it's by no means a fast or quick vehicle.

[tech3149]

16. EPA mileage figures are based on a test meant to approximate normal

driving situations. Most people never achieve the ratings of the EPA figures. That is primarily a function of driving style and skill. As an example, my 98 Civic (manual transmission) is rated for 32/37 mpg and my performance previously was 23/38 mpg. That was with a fairly aggressive driving style. Changing my driving style to try and improve my performance, I was able to improve city mileage to as much as 40mpg but never worse than the EPA's 32 mpg. On highway trips, I've managed 38 mpg at well above the speed limit. Keeping within the speed limit, I've gotten 42 mpg.

My sister has a 2005 Prius and averages 52 mpg and that's in heavy commuter traffic. Some of the "hyper milers" can get as much as 65 mpg from the Pris. I haven't paid much attention to the Civic hybrid, but I'm sure you could match or better those mileage figures.

I suppose the big question is how many miles you need to drive in a year and what type of driving you do. From what I've read, it takes about three to five years to break even between the purchase price versus fuel cost savings compared to a standard ICC engine. Since most people don't keep their cars for more than a few years, it might be hard come out ahead buying a hybrid. The more miles you drive a year, you're more likely you'll see a benefit from buying a hybrid.

[stevedeshazer]

18. I paid $1000 cash for my 1985 Honda Accord

I've paid about another $1000 to fix things, but it gets 33 mpg, and I haven't dumped it into a landfill yet.

I don't get how paying 30 grand or more helps the environment.

I just turned over 250,000 miles on the odometer. It passes the emission requirements.

What am I missing here?

[qdemn7]

19. Agreed

Much cheaper and better for the environment to keep an old car fixed and running than buy a new one.

Is your Honda using much oil?

[stevedeshazer]

21. A little, about a quart per 1000 miles

Doesn't leak, just burns a bit of blue smoke for the first minute after startup.

Part of the repair cost was replacing the cylinder head at just over 200k, but the block is original. This car's a tank in the best sense of the word.

[qdemn7]

23. Some advice

Based on my personal experience, when you replace or repair the head, the increased cylinder pressure might eventually require a complete engine overhaul because the pressure is forcing oil past the rings.

If you have to do an overhaul, and decide to keep the car long term, if might be cheaper simply to buy a complete engine, or engine and tranny from Autozone, OReilly's or other place. Then pay a mechanic do a swap rather than pay all the labor costs to do an overhaul. Also many engines come with a 1 year warranty.

[Gold Metal Flake]

20. Just for comparisons, my 2007 Focus is rated 27/34.

On the last tank I got 29 commuting with combined freeways and stop & go, as well as two trips over the mountains btwn the San Fernando Valley and the Santa Clarita Valley on the twisties. Not bad for a non-hybrid station wagon.

[Initech]

22. My '01 Grand Am gets 21 - 30

It's in decent shape but is starting to show its age. I'm hoping to sell it and replace it with a hybrid later this year.

[Writer]

25. My husband drives a civic hybrid which gets about 41-44 mpg.

It really depends on how you drive it. What especially cool about the civic hybrid is that the dashboard has a gauge that measures the average mpg as you drive.

[Clovis Sangrail]

26. the prius does as well

it shows estimated current mpg and avg mpg since last reset.