Your Fuel Economy Gauge Is Fibbing

[Dover]

As gas prices rise, drivers are paying closer attention to the fuel economy gauges that are found in most late-model cars as part of the trip computer. The only problem is that the gauges are inaccurate. In fact, Edmunds testing reveals that one such gauge claimed fuel economy 19 percent higher than the actual result.

Across two tests in seven different vehicles, the gauges were 5.5 percent inaccurate on average, according to data gathered by the editors at Edmunds.com.

The editors noted such optimistic estimates from fuel economy gauges during our 2009 and 2010 "Fuel-Sipper Smackdown." In two separate tests, editors drove five fuel-efficient cars from Los Angeles to Las Vegas and back under three different driving conditions: back roads (45-60 mph), city streets (stop and go) and highway (70-75 mph). During the tests (a total distance of more than 1,550 miles was accumulated by each car), the editors measured fuel economy by calculating how much gas was required to go a certain distance and comparing that to the reading on the fuel economy gauge...cont'd


http://www.edmunds.com/fuel-economy/your-fuel-economy-gauge-is-fibbing.html



Also heard from my sister that her Elantra, which was supposed to get 40mpg highway, only gets around 31 at most.She drives mainly on the highway (a long commute) without much traffic and said she maintains a pretty steady 65mph. Is this the exception or is this discrepancy common? That's seems like a big difference to me.

[TheWraith]

1. There's an easy way to calculate your "real" fuel economy.

Fill the gas tank, and hit the reset on your trip odometer. Go about your average driving for awhile. Then fill the tank again. Divide the miles traveled, per the odometer, by the number of gallons of gas you bought the second fill up. That's your "real world" average fuel economy.

[Dover]

3. Thanks for the tip. It's been so long since I figured real world mpg I'd forgotten how..lol. n/t

[FiveGoodMen]

2. My 2010 Jetta TDI is burning as much gas as it says it is

I've checked at the pump several times.

[Scuba]

4. I've been monitoring mine on and off for nearly 180,000 miles....

... and it's darned close. 2001 Explorer.

GPS provided some interesting info though. Two different brands (DeLorme, Garmin) show exactly same speed while the vehicle's speedometer under reports speed by 3-4 mph. That's counter to the "common knowledge" that "you're not really going as fast as the speedometer says".

[Tesha]

10. Do you have the factory standard-sized tires on the Explorer?

Oversize tires go farther per revolution so the
speedometer and the odometer both read low.

Does the odometer run true? If it does, then it's
just a bum speedometer.

Tesha

[Scuba]

11. I switched from AT to "road" tires, so may be smaller. I'll check the odometer against the GPS..

Thanks for that tip. I knew that tire size mattered, but had forgotten.

[Andy823]

5. I have a ford focus

The computer tells me I was getting about 3 miles more per gallon than when I figured it out myself the old fashioned way. Still not bad ad 33 MPG!

[Dover]

7. I thought Focus was advertised as getting around 40 mpg.

There are a handful of regular gas cars that are supposed to be getting that mpg. I know Hyundai has
three cars boasting that mpg. Is Focus another?
My sister thinks it's a bogus claim according to her own experience.

[doc03]

13. That's for the manual transmission Focus SFE model

the (FE) stands for fuel efficiency. Same as the Chevy Cruze the manual transmission (ECO) model gets 40 MPG. The ones with automatic transmission get a little less than 40 MPG.

[Dover]

15. I sat in one of these today (SE hatchback) and was impressed.

The dealership was right next to a store I was shopping in so I just did it on a whim.
I was swarmed by salesmen..lol. I thought it felt really comfortable, was attractive and was laid out nicely. This one didn't have all the bells and whistles according to the salesman but did have phone sych. It seemed to offer a lot for the money. And I just like hatchbacks for convenience.

[doc03]

6. My 2011 Chevy Cruze computer reads about 5% higher

than the actual calculated MPG. Not complaining about the fuel economy but the computer does overestimate the MPG. On a recent trip to the WV, MA and Va mountains I logged 700 miles and 33 MPG. That is pretty good for steep twisty mountain roads I think. I bought my Cruze in May and have 6000 miles on it so far without a single problem. It rides great and for a 1.4 L 4 cyl I was impressed at how it handled the mountain roads.

[Dover]

8. Have you gotten higher mpg on any type of road? I think Chevy Cruze

is one of those cars advertising around 40mpg hwy isn't it?

[doc03]

9. I have done a real 36 MPG on interstates in Ohio which is what

the EPA sticker says on my Cruze. I have the 2LT Cruze with a 1.4 turbo and automatic. They have an ECO model with automatic that does either 37 or 38 on the hwy and a 6 speed stick that breaks 40 MPG
hwy. I waited for months for the new Ford Focus and Honda Civic to come out then after trying them I drove the Cruze and it sold itself. So far I have had zero problems with it not even a squeek or rattle, great car. I haven't owned a Chevy since a lemon I bought 1977 and swore I would never buy another one, so I wasn't a die hard Chevy fan either.

[madokie]

12. One of my brothers has a Cadillac that the gauge shows he's getting 26 plus mpg

I asked him if it is correct and he said sure it is this is a cadillac. How do you answer that?

[TheWraith]

17. Actually, he might not be wrong about that.

I used to have an old, circa 1994, Pontiac Bonneville. It was a dozen years old, but when built, it was a cutting edge luxury car. And it weighed about 4500 pounds empty. The thing was a tank. Nevertheless, when I bought it, it got around 24 or 25 miles to the gallon. If I'd changed the air filter more, gotten an engine flush, fuel injection cleaned, etcetera, I probably would have hit 26 MPG easy even with it at that age.

An expensive car does have advantages over cheaper cars in terms of both performance and economy, primarily because more attention and labor goes into building it. The engine is more carefully built, more attention is paid to maximizing performance and torque, and better engineering minimizes wasted energy. All of that requires more cost, which is why it's not present on cheaper vehicles designed with more mass manufacturing.

You could probably build a stick-shift econobox type car that got 50 miles to the gallon, if you didn't mind paying as much or more for it than a Prius.

[Starboard Tack]

14. I have a 2005 Prius which averages about 53mpg, highway/city combined

Best I recorded was 66mpg on backroads averaging 40-45mph from central coast of Maine to Rochester, NY, via the Adirondacks.

[Dover]

16. Yep, Prius is still the best hybrid out there and has raised the bar for the others.

If I'm not mistaken I think Hyundai gets the best fuel economy for straight gas engine at 40mpg, with Ford Focus right behind.

[Codeine]

18. That's what the tripometer is for, doofuses.

There's even a calculator on your cellphone if you're mathematically impaired. Don't rely on everything to be done for you.

[Ready4Change]

19. None of this surprises me.

Cars factory speedometers are almost always wrong, almost always reading higher than your actual speed. It helps to sell cars. When you think you are going 65mph, but are actually doing 60mph, you think "wow, this car is smooth at 65mph."

Likewise, having a trip computer report that you are getting better fuel economy than you actually are gives you a warm fuzzy. In times of $4 gas, that's a car selling effect.

It stuns me, but I've come to realize that most people have no idea how to calculate fuel mileage on their own. Stuns me that, even without someone telling them how, they can't just sit for a moment and figure it out. I ran a casual mileage contest with my friends, and was dismayed that, even when I gave them clear instructions, they STILL couldn't. Some had no idea how to figure out miles driven from one tank full to another.

They are slaves to devices that do all that for them. We, as a society, are doomed.