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The diesel-powered Accord returned a remarkable 53 miles a gallon on the highway, 34 in the city and 44 in combined driving. (http://www.nytimes.com/2008/05/18/automobiles/autoreviews/18DRIVE.html?_r=1&ref=automobiles&oref=slogin)

http://www.cleanmpg.com/photos/data/501/Euro_Accord_iCDTi_world_record_holder.jpgLawrence Ulrich - NY Times - May 18, 2008

HONDA has spent decades establishing a reputation for fuel efficiency. But nothing in the company’s current lineup, including its Civic Hybrid, can match the mileage of the diesel Accord that I recently tested in and around New York City.

Minus its diesel powertrain, the European-market 2007 Accord that I drove is nearly identical to the car that Honda had been selling in the United States as the Acura TSX. That Accord should give a solid indication of the mileage and performance American consumers can expect when Honda offers a diesel option for the redesigned 2009 TSX.

The Accord — a demonstration car provided by Robert Bosch, the German technology company, to highlight its fuel injectors and other diesel components — returned a remarkable 53 miles a gallon on the highway, 34 in the city and 44 in combined driving. Those miles included a bumper-to-bumper crawl through Manhattan, the worst possible conditions for fuel efficiency.

The model I drove was powered by a 4-cylinder diesel displacing 2.2 liters and producing 140 horsepower and a stout 250 pound-feet of torque — the force that drivers feel pushing them into their seats under acceleration. That huge torque relative to the engine’s size is a main advantage of modern turbodiesels, making them well-suited to small economy cars and to burly S.U.V.’s that need torque for towing and hauling.

The America-bound Acura will use a new version of the 2.2-liter engine that I tested. The engine is notable for meeting 50-state emissions standards with no need to carry an onboard tank of urea, an ammonia-generating solution that other diesels use to scrub smoggy nitrogen oxides from the exhaust. Honda’s patented pollution system generates its own ammonia to fulfill the same mission. While that cleaner emissions system wasn’t installed on the Honda I tested, engineers expect it to have no discernable effect on fuel economy.

As with other diesels I’ve driven recently, the Honda’s frugal highway mileage and versatile power are important advantages over the typical hybrid. The Accord covered the zero-to-60 run in just under 9 seconds in my testing, which doesn’t sound spectacular on paper. But its passing power from 30, 50 or even 70 miles an hour was terrific, as the Honda easily shot past slower cars...http://www.nytimes.com/2008/05/18/automobiles/autoreviews/18DRIVE.html?_r=1&ref=automobiles&oref=slogin

Why dont they make a Diesel-hybrid?

They already feel that diesel in an accord means the car has to go upmarket due to pricing. Adding a hybrid to it would just push the price up that much higher. I would like to see a car with both, but I don't think it will happen at the accord level for quite some time.

Funny how up to now no one could build a 50 mpg car. I have a feeling with in the next 18 to 24 months we will be seeing eight to ten new 45 mpg or better cars coming from the major manufactures. With Honda's new bragging rights on this Accord others better step up to the plate with better mpg's or they will be left at the starting line.

Now... if we could only secure this vehicle for a more detailed "press review" ;)

Cheers;

MSantos

I would seriously consider a diesel TSX as long as it comes in a MT.

I second that, Manuel!

This would be one heck of a vehicle to play with but it is priced way out of range for me. I was so hoping they'd bring the Civic diesel over... at $18-19K or so it would have been the perfect replacement for my Elantra. It wouldn't get Insight numbers but it would be close -- with a back seat and nice "power" performance to boot!

Funny how up to now no one could build a 50 mpg car. I have a feeling with in the next 18 to 24 months we will be seeing eight to ten new 45 mpg or better cars coming from the major manufactures. With Honda's new bragging rights on this Accord others better step up to the plate with better mpg's or they will be left at the starting line.

They are already out there just the demand in US has not been great enough to bring them here:

http://carscoop.blogspot.com/2008/01/subaru-legacy-outback-boxer-diesel.html

A 4x4 wagon getting 40.6 combined.

"And as more hybrid owners are discovering, their cars deliver little or no mileage gain on the highway. That’s because battery packs and electric motors add several hundred pounds, and the system also contributes negligible energy at freeway speeds."

The old-style auto journalists still don't get it do they? The point of the hybrid is that the electric system allows one to use a smaller, more economical ICE optimized for power rather than torque because the electric system can add punch when needed. Hybrids DO get improved highway mpg over ICE-only vehicles as a result, even though the electric system is usually not contributing propulsion at highway speeds (if anything, on the highway a bit of power is flowing to the battery for trickle charging).

"And as more hybrid owners are discovering, their cars deliver little or no mileage gain on the highway. That’s because battery packs and electric motors add several hundred pounds, and the system also contributes negligible energy at freeway speeds."

The old-style auto journalists still don't get it do they? The point of the hybrid is that the electric system allows one to use a smaller, more economical ICE optimized for power rather than torque because the electric system can add punch when needed. Hybrids DO get improved highway mpg over ICE-only vehicles as a result, even though the electric system is usually not contributing propulsion at highway speeds (if anything, on the highway a bit of power is flowing to the battery for trickle charging).

Highway mileage numbers from fueleconomy.gov:

The big hybrids:
Prius - 45 (midsize)
HCH - 45 (compact)
Insight - 58 (two-seater)

Straight gassers:
Spectra - 32 (midsize)
Corolla - 37 (compact)
Smart ForTwo - 41 (two-seater)
My estimated average among midsize and large cars - 29
My estimated average among compact/subcompact cars - 32
My estimated average among two-seaters/minicompacts - 34

That's an increase of 20-40% above the best gasser in a comparable class, and (my estimate) 40-70% above the average in said class. Hybrids don't get better highway mileage, my a**. And of course, I can get 65 MPG out of my Prius in good weather on the highway, as opposed to 40 MPG out of a Malibu (a more average car). I'll take a 50% increase, thank you very much.

Why dont they make a Diesel-hybrid?Cost is the biggest reason. The price premium for diesel is $2-3k, and the price premium for a hybrid is $2-3k. Now you're talking $4-6k over a comparably equipped conventional gas car. Don't expect diesel-hybrid econoboxes anytime soon.

Also, remember how hybrids achieve their benefits. 3 ways, basically:

Allowing the ICE to be downsized while delivering comparable acceleration.
Recapturing energy lost during braking.
Avoiding idling.


The 1st benefit won't be quite as effective on a diesel, because the power delivery of an electric motor complements a gas engine better than a diesel engine. A torque-heavy electric motor gives a boost at low rpms when the gas engine is weakest and helps smooth power delivery. Diesels are strongest at low rpm and don't need as much help from the electric motor then. There isn't quite as much synergy to be had. I don't doubt there's a potential benefit but fully achieving it may require additional development such as gearing the electric motor higher than the ICE, as opposed to the in-line motor design used in Honda's current IMA system.

The 3rd benefit -- minimizing idling -- is also of reduced benefit in diesels because they already idle 2-3x more efficiently than gas engines.

And finally, a hybrid system and a diesel engine each add a couple hundred pounds of weight. On a small car you're dealing with a lot of extra weight to haul around, eating into the potential benefit. Also on a small car it's physically difficult to squeeze all that stuff in. My diesel Golf's engine compartment is crammed, despite a high hoodline and low ground clearance to make room for the bigger engine and accessories. There simply wouldn't be room to stuff in a hybrid drivetrain without extending the length of the car a few inches!

I'm not saying hybrid diesels aren't a good idea (I'd kill for one!), but I think the proportional mileage benefit is probably somewhat smaller than with gas engines, and when you figure in the extra cost it gets hard to justify on anything but a luxury car -- exactly the kind of car whose target market doesn't care as much about fuel economy anyway.

WriConsult - spot on.

But - the cost of both is declining. As the cost of oil increases ....

And there is some extra benefit for a diesel/hybrid - the diesel is really good at steady state - ie efficient (hence the great highway mileage). So the electric motor can handle transitions - where it is efficient all the time. A series hybrid makes the most sense with a diesel. In this setting - it might not need as much emission controls since it could be tuned to run at 1700 rpm all the time.

It does come down to the incremental benefit of going from 50 to 70 mpg. That just doesn't save much money on fuel. Like $240/10,000 miles at $4 a gallon. Now that is $2400 over 100k miles but you won't be able to get people to pay $2000 for that privilege - well some people but not many. Now at $8 a gallon (read Europe) - it might be worth it.

So the electric motor can handle transitions - where it is efficient all the time.

Is it? This is something I have been wondering about. Does anybody have any data re the efficiency of an electric motor at various rpms and under different loads?

Say you have a battery with a certain amount of energy in it. What is the most efficient way to utilize that electricity with an electric motor in order to maximize the distance traveled?

This gets into the question of whether a transmission (with its frictional losses) gives a net benefit with an electric motor? And whether wheel motors (assuming they would be "geared" at a single ratio) would work well.

I'd appreciate any thoughts about this.

300TT -- good point. I was thinking "inside the box". You're right that a series hybrid design would probably be a better match for a diesel. After all, that's basically the way diesel locomotives work.

Lightfoot -- good question. Most EV conversions I've heard of make use of the factory transmission. A lot of conversions lock the tranny into a single gear, but I've heard of cases where people retain the shifting ability and might use a couple different gears based on RPM -- so obviously the electric motor isn't equally efficient across its entire range.

Now you've got me thinking it's probably best not to run an electric motor through a gearbox at all. With the efficiency of an EV, the frictional losses in the gearbox probably do matter a bit. Would be better to select an optimal final-drive ratio and skip the gearbox entirely, so you're only converting the gear ratio once. For that matter, rollerchains (as on a bicycle, and that's why bikes use them) are substantially more efficient than the gears used in automotive gearboxes. If wheel motors don't result in optimal gearing, using a chain drive to provide the reduction might be most efficient.

Lads, Diesel my hole. They are fleecing us here in good ole Ireland. I suspect it is everywhere too. As it stands, diesel is euro1.35-1.40 per LITRE, Gas is 1.22-1.25. My crappy 16 year old civic is cheaper to run than my spanking new diesel kia cee'd. I've hypermiled the bag out of the kia and i cannot get it to run cheaper(over a tank) than the civic. Diesel is a con as far as i'm concerned. It might be cleaner burning but my pocket matters too. If you want to do the math: my kia: 5L/100k diesel @ 1.34 per litre.
De honda: 4.16L/100k Gas @ 1.22 per litre.

ollie

Lads, Diesel my hole. They are fleecing us here in good ole Ireland. I suspect it is everywhere too. As it stands, diesel is euro1.35-1.40 per LITRE, Gas is 1.22-1.25. My crappy 16 year old civic is cheaper to run than my spanking new diesel kia cee'd. I've hypermiled the bag out of the kia and i cannot get it to run cheaper(over a tank) than the civic. Diesel is a con as far as i'm concerned. It might be cleaner burning but my pocket matters too. If you want to do the math: my kia: 5L/100k diesel @ 1.34 per litre.
De honda: 4.16L/100k Gas @ 1.22 per litre.

ollie

A Kia diesel? I've never heard of it. But then again, I don't think Kia is a particularly fuel-efficient automaker. Aren't they the ones that advertised you'd forget where the gas tank was with only 33 MPG highway? :confused::eek:

If I got 33 MPG highway I'd **** a chicken.

Imagine a one liter turbo diesel in a two-seater like the Insight (taller though, say, the size of a Yaris). And then throw in a hybrid drive to help regenerate some of the energy lost. Retail price: $16-17k range.

100 MPG, anyone? With 90% of all my driving on the highway I'd snap it up in an instant.

Hi Lamebums, i think you're right there about the refinement of the kia. It sounds like an older model diesel. Next service i'm going to ask about a block heater to minimise the warm up time, and maybe a re-map....maybe...
Sorry about the rant about diesel. Just a little p***ed off after buying this new car that doesen't deliver the goods, mpg wise.
And next year i have to replace the civic. Had hoped on a diesel yaris but the kia has dulled the diesel shine somewhat.
Here's some info on the cee'd:
http://www.kiamotors.ie/~/media/Files/Upload/IE/cee%20d_sw%20feb%2008.ashx

ollie

Hi Lamebums, i think you're right there about the refinement of the kia. It sounds like an older model diesel. Next service i'm going to ask about a block heater to minimise the warm up time, and maybe a re-map....maybe...
Sorry about the rant about diesel. Just a little p***ed off after buying this new car that doesen't deliver the goods, mpg wise.
And next year i have to replace the civic. Had hoped on a diesel yaris but the kia has dulled the diesel shine somewhat.
Here's some info on the cee'd:
http://www.kiamotors.ie/~/media/Files/Upload/IE/cee%20d_sw%20feb%2008.ashx

ollie

I didn't see a listing for fuel economy on there, try to look that up if you get a chance. If your FE falls well short of what you're supposed to be getting, take it back to the dealer if it's a more recent car and say here's the problem, I'm not getting the mileage I'm supposed to get, here's how I drive, etc...

It might be wrongly tuned to run abnormally rich, or it could be a mechanical problem.

I think what happened with hybrids and some drivers is that they feel secure in driving aggresively since they're saving gas while doing so. Thus in the process they are running their gas engine much longer and harder and reducing their actual mpg. If they drove by the written rules of the road their mpg would be back up to the 40mpg range or higher.

Diesel here is also going high in price. I think I saw $5 for a gallon or 3.79 liters for 3.1735 euros.

Is it? This is something I have been wondering about. Does anybody have any data re the efficiency of an electric motor at various rpms and under different loads?

Say you have a battery with a certain amount of energy in it. What is the most efficient way to utilize that electricity with an electric motor in order to maximize the distance traveled?

This gets into the question of whether a transmission (with its frictional losses) gives a net benefit with an electric motor? And whether wheel motors (assuming they would be "geared" at a single ratio) would work well.

I'd appreciate any thoughts about this.I'll take a stab. I don't have "data" per se, but I'll give you what I do know. I don't think electric motors have the same type of mechanical losses and gearings that ICEs do. Basically 10k RPM is less efficient than 1k RPM because of the mechanical losses intrinsic in spinning anything at 10k RPM as opposed to 1k RPM. Now as far as acceleration goes, there are thermal inefficiencies that get thrown in when you pump too much current through a wire. So quick bursts of power will have a loss associated with them as well.

The odd part is that all these "losses" under the hood are going to pale in comparison with all the losses outside the hood (wheels, tires, wind drag, weight). Another HUGE point of loss will be the battery round trip efficiencies. Batteries chemistries and technology vary widely in this regard. So if you convert 10W of electricity to chemical potential (battery), how many Watts can you get back out? It won't be 10W but something less than 10W.

Also keep in mind Inverter inefficiencies. Most batteries I've seen get charged by DC, and most houses are powered by AC. Inverter (turns AC to DC) usually loose 5-20% of their energy just doing the conversion. So you loose some going from AC to DC, you loose some going from DC to battery, you loose some going back from battery to MPH (acceleration) and you loose some going from MPH to battery deceleration. I think those are your biggest losses and probably much more prevalent than the inefficiencies of the electric engine itself.

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Dan - I think you are right.

We have grown so used to inherent ICE inefficiences. The electric motor of course has its own losses but they are much less than an ICE. Yes - there are transmission and conversion losses. Once that is done - there are less losses at the point of conversion from electricity to motion then say from gasoline to motion. I agree that spinning at 10,000 rpm is going to cost more in friction losses than 1,000 rpm.

I'll take a stab. I don't have "data" per se, but I'll give you what I do know. I don't think electric motors have the same type of mechanical losses and gearings that ICEs do. Basically 10k RPM is less efficient than 1k RPM because of the mechanical losses intrinsic in spinning anything at 10k RPM as opposed to 1k RPM. Now as far as acceleration goes, there are thermal inefficiencies that get thrown in when you pump too much current through a wire. So quick bursts of power will have a loss associated with them as well.

The odd part is that all these "losses" under the hood are going to pale in comparison with all the losses outside the hood (wheels, tires, wind drag, weight). Another HUGE point of loss will be the battery round trip efficiencies. Batteries chemistries and technology vary widely in this regard. So if you convert 10W of electricity to chemical potential (battery), how many Watts can you get back out? It won't be 10W but something less than 10W.

Also keep in mind Inverter inefficiencies. Most batteries I've seen get charged by DC, and most houses are powered by AC. Inverter (turns AC to DC) usually loose 5-20% of their energy just doing the conversion. So you loose some going from AC to DC, you loose some going from DC to battery, you loose some going back from battery to MPH (acceleration) and you loose some going from MPH to battery deceleration. I think those are your biggest losses and probably much more prevalent than the inefficiencies of the electric engine itself.

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Don't most of the losses you mention (save for the inverter inefficiences) also apply to ICEs as well?

I hope I didn't give the impression that I was anti-electric motor; if anything I'm in favor of plug-ins and EV's. I was just trying to figure out how the parameters of extracting the maximum from a given amount of chemical energy stored in a battery would differ from doing the same thing with a given amount of gas using an ICE. Upstream inefficiencies from inter-conversions and charging the battery were not part of what I was wondering about.

A friend pointed out that heat production in an electric motor goes as the sguare of the current, so higher voltage motors are more advantageous - except that more insulation is needed at higher voltages, which adds weight and limits space in the motor. Higher rpms may be less efficient from an electrical point of view (in addition to frictional losses) but we're not sure.

Some thoughts:

- Wheel motors might have an advantage in that the front two could be "geared" differently from the rear two, one pair optimized for starting out and low speeds, the other for higher speed operation? Maybe this could be more efficient that a single motor running at a range of rpms, or a single motor with a gearbox?

- A CVT might be handy but I read somewhere that they may not handle the low rpm torque of an electric motor, and not sure about efficiency losses in them?

- Freewheel? Might be an advantage to build in coasting via a clutch so that foot-off-the-accelerator would not necessarily lead to regen and slowing down? IOW, P&G might improve "mileage" for electric motors too? But you'd want to capture regen via braking.

My understanding is that P&G is effective with an ICE because of the efficiency peak under load. This just isn't nearly as pronounced in an electric engine, but you could still benefit from coasting with no energy use at all to take advantage of the terrain (downhills).

Don't most of the losses you mention (save for the inverter inefficiences) also apply to ICEs as well?Inverter, Chemical and Current losses are all unique to electric engines. But ICE engines have inefficiencies with timing ignition and fuel mixtures that are unique to ICEs. There delta between peak and off-peak efficiencies in an electric engine is much smaller than that same delta in an ICE.

A friend pointed out that heat production in an electric motor goes as the sguare of the current, so higher voltage motors are more advantageous - except that more insulation is needed at higher voltages, which adds weight and limits space in the motor. Higher rpms may be less efficient from an electrical point of view (in addition to frictional losses) but we're not sure.I think the Toyotas have a DC to DC inverter so they can pump wattage at one voltage, but then use use at a different voltage.

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