Honda Fuel Economy

[adlep]

I got a new car (to me at least)
It is a 2006 Honda Accord SE Sedan with a manual transmission (will post some pics tomorrow) with 26000 miles on it.
I am upgrading from my current car - 96 Civic Hatchback DX so the Accord feels like a limo to me...
I thought that I am actually getting a Mazda6 but the deal for the car I wanted did not go through so I ended up with the Accord.

Anyway, I am bit puzzled about fuel economy rating...
The 2006 Accord is rated at 26/34.
I actually got a better highway result of 35.8 MPG going at around ~70MPH from Chicago to Detroit (305 miles) with the cruse control engaged and NO traffic.

On the other hand, the new 2009 Honda Fit is rated at 27/34

My question is, how is such a fuel efficiency rating possible for these 2 vehicles?

It seems to me that the Fit's MPG rating is severely underrated. It is almost physically impossible to get the same MPG rating out of the 2.4 litter Accord's engine AND the 1.5 litter Fit's engine. Not to mention the fact the the Fit must be at least 300 lb lighter than the Accord...
?

 

[Howard]

How are you measuring?

 

[EightySix Four]

The new EPA results attempt to simulate more realistic driving in their accelleration. The Accord can accellerate to the necessary speed in the necessary time without breaking a sweat. The Fit is working it's balls off all the way until that speed.


45% throttle to accellerate to 60 in the desired amount of time uses less fuel than a car at 100% throttle to make it.

That's also one of the reasons I believe vette's get great gas mileage on the testing (besides weight, aerodynamics, and gearing of course)

 

[dug777]

Originally posted by: crazySOB297
The new EPA results attempt to simulate more realistic driving in their accelleration. The Accord can accellerate to the necessary speed in the necessary time without breaking a sweat. The Fit is working it's balls off all the way until that speed.


45% throttle to accellerate to 60 in the desired amount of time uses less fuel than a car at 100% throttle to make it.

That's also one of the reasons I believe vette's get great gas mileage on the testing (besides weight, aerodynamics, and gearing of course)

My understanding is that 100% throttle is technically more efficient.

Of course, rpm is the elephant in the corner of the room

Having acres of torque and being able to tick over when cruising on the highway is a significant part of a corvette's relatively excellent highway fuel consumption.

 

[AnnonUSA]

the EPA fuel ratings were changed to be more realistic last year I believe.

Honda's love open highway, constant speed driving....I got about 34 mpg in my Acura TLs on a trip up Rt95 some years back...Average speed about 75, manumatic Trans locked in the 5th gear position as much as possible. That same car would only get about 18 to 20 mpg around town.

I can pull 28 mpg out of my 2000 accord on the highway (I don't drive speed limits), normally about 22 mpg average all around.

 

[Throckmorton]

Voodoo engineering is all I can think of. Gas mileage is really mysterious. A Honda Accord gets better gas mileage than a Miata that weighs half as much, even in the city. And a lot of FWD econoboxes max out at 25mpg. It's like gas mileage just wasn't a concern back before prices rose, so if the engineers could squeeze out an extra 5 horsepower at the expense of 30% of gas mileage, they would.

They also insist on gearing cars so you can have "passinig power" in top gear, maybe because focus groups don't like downshifting.

 

[Gibson486]

Originally posted by: Throckmorton
Voodoo engineering is all I can think of. Gas mileage is really mysterious. A Honda Accord gets better gas mileage than a Miata that weighs half as much, even in the city. And a lot of FWD econoboxes max out at 25mpg. It's like gas mileage just wasn't a concern back before prices rose, so if the engineers could squeeze out an extra 5 horsepower at the expense of 30% of gas mileage, they would.

They also insist on gearing cars so you can have "passinig power" in top gear, maybe because focus groups don't like downshifting.

no no....mazda is just bad when it comes to gas mileage...

<---- Mazda3 owner.

 

[Demon-Xanth]

Originally posted by: dug777

Originally posted by: crazySOB297
The new EPA results attempt to simulate more realistic driving in their accelleration. The Accord can accellerate to the necessary speed in the necessary time without breaking a sweat. The Fit is working it's balls off all the way until that speed.


45% throttle to accellerate to 60 in the desired amount of time uses less fuel than a car at 100% throttle to make it.

That's also one of the reasons I believe vette's get great gas mileage on the testing (besides weight, aerodynamics, and gearing of course)

My understanding is that 100% throttle is technically more efficient.

Of course, rpm is the elephant in the corner of the room

Having acres of torque and being able to tick over when cruising on the highway is a significant part of a corvette's relatively excellent highway fuel consumption.

The lack of pumping losses lose to a richer air fuel mixture. Diesels are "full throttle" all the time because they control their engine speed through the amount of fuel going into the engine rather than having a throttle body. This is also why a two stroke diesel can over-run if there's an oil leak as well as the oil well fire fighting equipment can't run if there's methane in the air (the engine will just run as fast as it can until it blows).

Part of the reason that the Corvette gets great gas mileage is that although it has a big V8, that engine is operating in a vacuum most of the time due to the large amount of low end grunt and the tall gearing. The light weight doesn't hamper anything.

An engine is an air pump, and computers tend to try to make a ratio of 14.7:1. So the more air in, the more fuel you gotta put in. Closed throttle blades mean less air gets in, so less fuel gets in.

That's also why there's a kind of ceiling on motorcycle MPG. High end bikes get high 30's, plenty of bikes get in the 60's, a few in the 70's, but to get into the 80's requires a lot of compromises, and 100's is something even most scooters can't do.

 

[adlep]

Interesting discussion, but honestly I am still confused...
It may however have something to do with the torque. Bigger 2.4 engine has to "work less" to move the car versus the small 1.5 engine that has to work on higher RPMs more often (?)...

 

[Demon-Xanth]

Originally posted by: adlep
Interesting discussion, but honestly I am still confused...
It may however have something to do with the torque. Bigger 2.4 engine has to "work less" to move the car versus the small 1.5 engine that has to work on higher RPMs more often (?)...

Honda put a lot of work and more money into the 2.4, the 1.5 doesn't have the same level of refinement. But is notably cheaper.

 

[vshah]

i'm pretty sure the fit will get at least a few mpg higher than its 34 rating on the highway. kids in regular civics can hit 38. i'd be willing to bet some people can hit 40 in their fits

 

[PingSpike]

I always look at the EPA ratings of the fit and go "What exactly is the point of this thing?"

 

[Zenmervolt]

Originally posted by: crazySOB297
The new EPA results attempt to simulate more realistic driving in their accelleration. The Accord can accellerate to the necessary speed in the necessary time without breaking a sweat. The Fit is working it's balls off all the way until that speed.


45% throttle to accellerate to 60 in the desired amount of time uses less fuel than a car at 100% throttle to make it.

That's also one of the reasons I believe vette's get great gas mileage on the testing (besides weight, aerodynamics, and gearing of course)

Actually, not true. 100% throttle on a gasoline engine minimises parasitic pumping losses. It's actually more efficient to run an engine neat WOT (modern EFI runs a richer mix at full WOT, which tends to negate the increased pumping efficiencies, but that's really more academic). When the throttle is even partially closed, it requires that some additional horsepower be used to pull air past the restrictive throttle plate, and additional horsepower always means additional fuel burned. The ideal situation for a gasoline engine's efficiency is a throttle opening of 75% to 95% coupled with low RPM.

The reason that the Fit gets poorer mileage is that its engine must rev to a higher RPM. RPM is the "800 pound gorilla" in the fuel economy equation.

That said, the new EPA ratings under-rate. In my experience even the old EPA ratings under-rated and the new ratings are horrible. I have never owned a car that did not exceed the old-style EPA ratings. The new EPA ratings are consistently 3-4 mpg lower than I can realistically achieve. For example, my Volvo is rated (revised ratings) at 18/25. I have never gotten below 21.5 mpg and on the highway with cruise control I will see 28 mpg on long trips.

ZV

 

[ElFenix]

using the new ratings the 2006 accord manual does 23/31.

Originally posted by: adlep
I got a new car (to me at least)
It is a 2006 Honda Accord SE Sedan with a manual transmission (will post some pics tomorrow) with 26000 miles on it.
I am upgrading from my current car - 96 Civic Hatchback DX so the Accord feels like a limo to me...
I thought that I am actually getting a Mazda6 but the deal for the car I wanted did not go through so I ended up with the Accord.

Anyway, I am bit puzzled about fuel economy rating...
The 2006 Accord is rated at 26/34.
I actually got a better highway result of 35.8 MPG going at around ~70MPH from Chicago to Detroit (305 miles) with the cruse control engaged and NO traffic.

On the other hand, the new 2009 Honda Fit is rated at 27/34

My question is, how is such a fuel efficiency rating possible for these 2 vehicles?

It seems to me that the Fit's MPG rating is severely underrated. It is almost physically impossible to get the same MPG rating out of the 2.4 litter Accord's engine AND the 1.5 litter Fit's engine. Not to mention the fact the the Fit must be at least 300 lb lighter than the Accord...
?

 

[thomsbrain]

What Zen said.

 

[swtethan]

Yeah.... I cant get 30mpg in my civic si.

 

[randay]

power, weight, transmission, and aerodynamics. these all affect mpg.

i drive a fit so i can tell you that the power is severely lacking, the gearing is on the short side, going anywhere above 60mph will hamper your fuel efficiency, and also its a big box so the aerodynamics cant be good. for instance there is a mountain road i drive up and down regularly, in my old volvo s40 it would roll downhill and easily reach 80mph off power, where as my fit barely hits 60mph under the same driving input (dfco downhill).

on the fit forums i frequent the fact that the civic gets better mpg with a bigger motor and more power is a major point of discussion and discontent.

 

[vi edit]

I'm still happy that my crusty old SOHC 3.5L GM cast iron clunker mated to an archaic 4 speed transmission is able to pull 32MPG with ease @ 65MPH.

 

[angry hampster]

Originally posted by: Throckmorton
A Honda Accord gets better gas mileage than a Miata that weighs half as much, even in the city. .

Originally posted by: swtethan
Yeah.... I cant get 30mpg in my civic si.

I've never understood why people complain about getting poor mileage in sports (sporty) cars.

 

[BassBomb]

I have 2007 Accord EX-L 4cyl

I get 39MPG going 100km/h (speed limit) all highway
I get 30MPG going 140km/h all highway

My Civic was doing 33MPG @ 140km/h same route

 

[Throckmorton]

Originally posted by: angry hampster

Originally posted by: Throckmorton
A Honda Accord gets better gas mileage than a Miata that weighs half as much, even in the city. .

Originally posted by: swtethan
Yeah.... I cant get 30mpg in my civic si.

I've never understood why people complain about getting poor mileage in sports (sporty) cars.

Because if you drive the sporty car like you drive the big sedan, theoretically you should get better gas mileage, because the engine is burning less fuel to accelerate it the same amounts. But that's not what happens. There must be some inefficiency somewhere.

 

[Zenmervolt]

Originally posted by: Throckmorton

Originally posted by: angry hampster

Originally posted by: Throckmorton
A Honda Accord gets better gas mileage than a Miata that weighs half as much, even in the city. .

Originally posted by: swtethan
Yeah.... I cant get 30mpg in my civic si.

I've never understood why people complain about getting poor mileage in sports (sporty) cars.

Because if you drive the sporty car like you drive the big sedan, theoretically you should get better gas mileage, because the engine is burning less fuel to accelerate it the same amounts. But that's not what happens. There must be some inefficiency somewhere.

Gearing. When you're turning 3,000 RPM at 60mph you're going to use more fuel than the big sedan that's only turning 2,100 RPM.

High-RPM combined with part throttle is a horribly inefficient mode for a gasoline engine. Sporty cars are geared shorter to keep the engine in the fatter part of the powerband (this is especially important in cars like the Civic Si that are short on torque and compensate with shorter gearing). Larger cars are usually set up with a very tall overdrive to set them closer to the low-RPM, larger throttle opening mode that is more efficient and the increased torque of their engines allows this to be done with less affect on passing acceleration.

ZV

 

[Jumpem]

The EPA rating system changed for 2008+ model year vehicles. You can't directly compare the two measurements.

 

[cheesehead]

Originally posted by: PingSpike
I always look at the EPA ratings of the fit and go "What exactly is the point of this thing?"

Cheap, practical, safe, not bad to drive. A neighbor has one, and loves it to death. Of course, she only uses it around town (her husband drives something larger), and she's in her sixties.

Originally posted by: Gibson486


no no....mazda is just bad when it comes to gas mileage...

<---- Mazda3 owner.

My dad managed 37MPG on a 650 mile winter trip in his mazda3. Of course, this is an obsessive-compulsive freak who performs rituals of automotive break-in voodoo, and barely ever even touches the accellerator. (His one complaint is "I wish I could've bought it with a smaller engine - this one is unnecessarily large.")

Originally posted by: angry hampster

I've never understood why people complain about getting poor mileage in sports (sporty) cars.

There's always the Miata. Or the Lotus Elise....

Originally posted by: Zenmervolt

Gearing. When you're turning 3,000 RPM at 60mph you're going to use more fuel than the big sedan that's only turning 2,100 RPM

Yep. On the other hand, the light weight and low drag of the Fit make it much more practical for its' primary purpose - hauling groceries around town.

That said, I'd much rather have a 4-door civic hatchback.

 

[hans030390]

Originally posted by: swtethan
Yeah.... I cant get 30mpg in my civic si.

You CAN...you just aren't doing it right.