Hybrid Cars to Get New Mileage Ratings

Skidge writes "Wired is running a piece showing the drastically reduced mileage ratings for hybrids after the upcoming changes in gas mileage calculations by the EPA. While the cars themselves aren't changing, plugging these new numbers in to the equation makes a hybrid much less cost effective: "The two top-selling hybrid vehicles, the Prius and Honda's Civic Hybrid, will lose 12 and 11 miles per gallon respectively from their city driving estimates." The new values come from more realistic testing; the old, over-inflated ratings were higher in part because the cars idled a lot, allowing the hybrids to completely turn off their engines. The new ratings should be more in line with what hybrid drivers are actually seeing."

How to drive a hybrid

[Anarchysoft]

I thought the key to getting good mileage with a hybrid was understanding how to drive it properly and, when that was done, folks were getting close to the listed mileage.

Not just for hybrids

[PaisteUser]

It's important to note that these new ratings also change the mileage estimates for pure gasoline engines as well.

not just hybrids

[Chris Chiasson]

As I understood it (a few years ago), the tests were not changed for a long time for several reasons, among them were easy comparisons to old data. Also, AFAIK, the test MPG numbers were already automatically scaled back by 20% (for all cars) before being placed on window stickers. By the way, I think all cars were benefiting from the tests (because the tests didn't reflect real world driving and tended to overestimate the MPG) - it is just that hybrid cars were really able to abuse the tests.

Online consumer MPG submited database

[RingDev]

For 'real world' numbers: http://www.greenhybrid.com/compare/mileage/ [greenhybrid.com]

-Rick

Strange but true

[SheldonLinker]

Unlike most cars, the Prius gives enough feedback to actually help. By learning how the car works, I'm actually getting 2 MPG better than the posted ratings for city driving.

On the flip side of this, I just got back from a trip, Irvine to Phoenix and back, and the actual MPG was 3 MPG less than the posted ratings. However, that was with the air conditioner set at 72F and High.

Accurate for my single data point, anyway

[raygundan]

My wife's Prius is averaging right around 47mpg in mixed city/highway driving after about two years. She doesn't do anything special while driving-- just treats it like any other car. Since the new rating is 48/45/46, it sounds like they're right on the money.

It's about damn time the EPA revised their ridiculously inaccurate tests. The data has been off for years, for all cars.

There are alternatives to the EPA numbers

[delirium28]

There's a hybrid database that I've been scanning over the past year or so to see exactly which hybrid is "worth" the extra cost (ignoring the environmental impacts of course, since I'm a greedy capitalist pig ;-))

Hybrid Mileage Database [greenhybrid.com]

So far the EPA numbers in TFA seem to line up well for the Prius at least, but I haven't looked at any of the other numbers.

Re:Sampling?

[michrech]

Catch-22. They like to have a "real" number before the car starts selling, but via your method they'd need to sell enough to get an accurate sample.

Many cars are driven around in "normal situations" by test drivers. Many car magazine photographers do their best to try to get snaps of these cars.. They could use the data from these cars to do their estimates. For cars that aren't test driven, they could start.

My car (an '07 Caliber) was rated at "28 to 32 MPG". I consistently get 26 or less. :(

Re:How to drive a hybrid

[BendingSpoons]

I thought the key to getting good mileage with a hybrid was understanding how to drive it properly and, when that was done, folks were getting close to the listed mileage.

Not really. I drive an '06 Civic Hybrid, which is listed at 49mpg city/50mpg highway. I am a very fuel-efficient driver and I get - at the most - 42 mpg when I drive around Philadelphia. And that's when I'm pissing off every driver behind me by accelerating slowly/coasting/etc. And under optimal weather conditions.

The highway estimate is a little more accurate. Cruising at 65-68 mph under optimal conditions (no AC, etc.) I usually get around 47 mph.

It's also kind of funny how much the weather affects my MPG. Cold weather drops me down at least 5 MPG. I'm not sure if that's particular to hybrids, or if that's every car.

Diesel!

[spud603]

We have a 2003 VW Jetta TDI, and we consistently get 40-45 MPG. If I drive very conscientiously I get over 50 MPG. As I understand it, the main reason that diesels aren't picking up in the US is that the EPA restricts their sale: car companies can only sell up to a certain percentage of their fleet as diesels. Demand for them cannot legally be satisfied, so they are not marketed at all.
Add to this the facts that diesel fuel requires less energy to produce, and can be made (mostly) renewably from just about anything that grows, and diesels blow hybrids out of the water in terms of fuel efficiency.
Maybe this change in rating schemes will take some of the marketability out of hybrids and raise awareness for diesel... though more likely it will just encourage people to say fuck it and buy an RV to drive their kids to soccer practice.

Re:How to drive a hybrid

[Red Flayer]

Temperature also affects tire pressure. Until you've driven quite a bit on a cold day, your tires are probably underinflated, thus decreasing your fuel efficiency.

Re:How to drive a hybrid

[rolfwind]

Season/temperature affects different things.

In the summer, many cities and surrounding counties mandate a 85%/15% gas/ethanol mixture in order to reduce pollution. This has the effect of making the gas more expensive, but Consumer Reports also found that in regular cars - it kills the MPG by up to 30% because of ethanol's lower energy potential making it actually worse than pure gas.

That, however, does not explain your lower MPG in the winter. This is actually pretty easy - the colder your engine is on start-up, it will take more fuel until it heats up. I am not just talking about idling while waiting for the car to heat up. The gas/air mixture just doesn't burn as efficiently in a cold cylinder/piston. Part of the reason is the fuel/air mixture does not atomize as easily as in warm weather, and so this is an effect that will be through driving as the air will be always delivered cold.

The cold weather/cold start effect is partly eliminated by the Toyota Prius as it stores the radiator fluid (once the car is turned off) in a insulated thermos type of device, to heat the engine up as rapidly as possible on start up.

You also have to figure that all the ball bearings in your car are greased up, and thus they have more drag in the cold weather. That a little thing. Then tire pressure may be too low, as air is denser - on a typical sedan you need about 32 psi to get optimal fuel efficiency. And a tire that is at 32 in 70+ degree weather may be below 29 in the freezing cold.

Cold weather can also be a positive - the air is denser, and that gives a small effect (like free low pressure supercharging/turbocharging) that can increase the horse power of your engine. But the effect is small.

Lots of factors.

Re:Sampling?

[homer_ca]

The EPA test is actually pretty accurate if you drive exactly like the test cycle, but the test conditions are nothing like real world driving. The city cycle averages about 21mph with very mild acceleration. The cold start occurs at 75 deg F (cold starts in colder weather burn much more gas). The A/C and heater are not used. The highway test has a similar leisurely pace. It averages 48mph with mild acceleration. Anyone merging and driving in freeway traffic that slowly would be a serious road hazard.

See here [caranddriver.com] for more info about it.

Re:Sampling?

[robpoe]

The EPA doesn't actually test the cars under real situations.

The car manufacturers test their OWN cars, but not in real-world. They put them on a Dynamometer, drive it in varying conditions, and collect the carbon it produced. From that, they calculate how much fuel the car burned and then derive the MPG from that.

Of COURSE a hybrid would SHOW a huge MPG rating by that government standard. A total electric would show ~ (infinity) as it produces NO carbon itself.

Oh, and for anyone who thinks I'm just blowing smoke out of my ass (pun intended)

http://www.fueleconomy.gov/feg/how_tested.shtml [fueleconomy.gov]

Re:Realistically

[Anonymous Coward]

Simple. By reducing pollution we reduce the need for medical services related to said pollution. All too often, side costs are ignored. If we could all drive more efficient less crap generating vehicles, you can bet over time a number of respiratory issues will start to drop. Of course, we won't change and asthma cases will continue to rise.

Re:You must be new here.

[jridley]

E85 cars are mainly a gimmick. The auto manufacturers love it because they get to make a practically free change (some extra computer firmware and maybe a specific gravity detector for the fuel) and they get to count it as a vastly higher mileage car; I think they get to rate it as though it was only burning the 15% of gas that it does (IE 20 MPG / 0.15 = 133 mpg), even though the vast majority of E85 cars that are sold will never see a drop of E85, and even though burning ethanol releases even more greenhouse gases than burning gasoline does; you burn 80% as much fossil fuels to make a unit of ethanol as the amount of energy that's in the ethanol, then you have to actually burn the ethanol.

Don't even get me started on hydrogen.

I'm waiting for a good electric, myself. The could make a damn sweet one for a decent price if they wanted to. I have friends who are driving electrics made 10 or more years ago that would work fine for many people, but they're expensive because not many are made. Electrics at least have the POTENTIAL to be really clean.

Re:Realistically

[ArsonSmith]

But then the hybrid owner is also lowering the cleanup costs from impact to the environment. Those will be shared by all as well.

A/C versus open windows

[name_already_taken]

Do you drive with your windows down or the air-conditioner on a lot (it creates more drag or needs more energy to use)?

I've read that modern car air conditioning uses less energy than the additional aerodynamic drag created by driving with the windows open - although if the car is moving at low speed or sitting still then the economical choice is the windows, although they don't work as well to cool the interior of a car stopped or moving at low speed, unless it there is a good wind.

Air conditioning systems have undergone steady improvements in efficiency (cycling clutch, better temperature and pressure controls, variable displacement compressors, etc), whereas open windows (as a cooling device) have generally not been made more efficient.

Re:Sampling?

[Smidge204]

This is a rather important point many people don't understand. Driving the speed limit and driving defensively save gas.

Some anecdotal evidence of mine... I drive a '93 Dodge van with over 220K miles on it. It has an onboard computer that tells me both instantaneous and average MPG, so I decided to experiment.

Driving "normally" I got 11.3 MPG average over two weeks. Then I started using cruise control, whenever possible, set at the speed limit. Coasting whenever possible (I'm never in a hurry to get up to a red light anyway), not accelerating as hard and trying to avoid accelerating up hills. My next two-week average was 14.7 MPG.

Since my average commute is a little over 5 miles, I'm nearly 2 gallons of gas per week less than before... or about $7/week at current prices. That's worth it IMHO.
=Smidge=

Re:Mileage has not improved in 10 years!

[Anonymous Coward]

Apples and Oranges, man. A civic is MUCH bigger than your Metro. That's like comparing a KIA Sephia to a Hummer. They aren't the same.

Re:Strange but true

[cens0r]

They didn't discontinue the echo, they just renamed it. Get a Scion or a Yaris and you end up with the same car.

Re:It uses the full tank as a baseline, not empty.

[Tiber]

Since gas nozzles are basically standardized and tend to click off at the same point, this isn't a terrible assumption

Actually that's incorrect. The pump relies on the air pressure in the tank to figure out when it's full. As you're filling the gas tank, the pump is pulling the vapors out of your tank. When the pump has a hard enough time pulling the vapors out, it assumes the gasoline is moving slower down the fill neck because the level of the gas in the tank is higher. Obviously this is going to totally be botch depending on the tempeture of the fuel in your tank, the tempeture of the air, the difference between the tempeture inside and outside your tank, the altitude you last filled your tank at, and how safe the owner of the pump wants to be in terms of aggressively filling your tank.

Short of filling your tank until you see gas spraying out, you have no idea what the level of gas in the tank is when it "clicks off".

And moving averages

[wsanders]

Or just run a moving average - add the mileage and gallons consumed up for the last 5 fill-ups and you will iron out any variations.

Useless data: 1999 Honda CR-V, varies from 21 to 25 MPG or so, the moving average is consistently 23.5, except when I go on a long trip that burns more than one tank.

Re:How to drive a hybrid

[qval]

Funny how your replied to a topic "How to drive a hybrid" with this:

"I get - at the most - 42 mpg when I drive around Philadelphia. And that's when I'm pissing off every driver behind me by accelerating slowly"

Use some common sense!

You're supposed to accelerate briskly with a hybrid, so that you get the drive train to offer you extra torque from the electric motor. This allows you to get up to speed quickly and efficiently. Then you simply maintain speed.

I'm not telling you to slam your pedal to the carpet. I'm telling you to accelerate at a reasonable to quick rate. Jack rabbit start it's not, but it is quick.

Try this for a tank or two, You'll probably get better mileage and piss off the others on the road a bit less.

Oh, and another point. Coasting isn't the best either. You should brake slowly coming to a stop so you fill up your batteries again. then the quick start you're about to do is almost free!

Re:Sampling?

[drinkypoo]

If the AC, radio, onboard navigation, lighting etc are using more energy than the than actual movement of the car, your mileage will be lower.

The AC is by far the biggest power-using accessory in the vehicle, with the possible exception of power steering which uses a very high-pressure hydraulic system (Except in some new cars which use electric power assist.) At higher RPMs the AC system can use as much as five horsepower - about 3.8kW or 316W. In other words there's no point in even mentioning anything but the AC - which draws maybe 1/4 as much as the amount of power it takes to keep an aerodynamic vehicle moving down the road at freeway speeds. This is why you might as well use your A/C if you're on the freeway - opening your windows destroys your aerodynamics and increases drag remarkably.

But anyway, it is nearly impossible to have accessories consuming more power than motion... Unless you're parked, or going so slowly that you're wasting more power idling than moving.

Re: Hybrids

[buraianto]

Don't know where you're getting your information. The batteries are warrantied for 8 years/100,000 miles.

From http://www.toyota.com/vehicles/2005/prius/faq.html [toyota.com]:

Toyota has extreme faith in our hybrid technology, so Prius comes standard with the following coverage:

Basic: 36 months/36,000 miles (all components other than normal wear and maintenance items).

Hybrid-Related Component Coverage: Hybrid-related components, including the HV battery, battery control module, hybrid control module and inverter with converter, are covered for 8 years/100,000 miles. The HV battery may have longer coverage under emissions warranty. Refer to applicable Owner's Warranty Information booklet for details.

Powertrain: 60 months/60,000 miles (engine, transmission/transaxle, front-wheel drive, rear-wheel drive, seatbelts and airbags).

Rust-Through: 60 months/unlimited miles (corrosion perforation of sheet metal).

Re: Hybrids

[metamatic]

Freeway speeds such as 70mph will IN FACT put you into the SUV mpg territory. And that is a single person no load condition. Load 4 passengers and all their gear for a 4 day weekend- and you are in fact at SUV MPG.

Utter horsehit. I drove a Prius from MA to TX, it was almost all freeway driving at 55-70 mph. Not only that, there were two of us in the car, and the back was entirely filled with cargo, seats folded flat. (We were moving.)

We averaged 47mpg.

Take your Detroit astroturf FUD elsewhere.

Re:Sampling?

[toddestan]

If so, here's your cluebat: Unless the electric component is bringing in power from outside the system, the test is completely valid, because all the power comes from the gasoline in the tank. Turning the engine into a generator which powers and electric drive-train doesn't change this simple fact.

Actually, it's not that simple. If the hybrid goes into the test with a mostly charged battery pack, and at the end of the test the battery pack is depleted, then the hybrid "cheated" by using stored up energy that it generated before the test began. Naturally, the effect would get worse the shorter the mileage test is. Of course, the hybrid could also be penalized if it goes into the test with a depleted battery pack, and by the end of the test had burned extra gasoline to charge it up. The only way to be fair would be to end the test with the battery pack at the same state as when the test began, or to run the test long enough (several hours?) that the effects from residual charge in the battery can be ignored.

Though my impression is the reasons hybrids do so well is that they are able to kill the gasoline engine and emit no carbon during parts of the test when a normal car would be idling its engine.