How can they improve the fuel economy of the next generation Pruis?

All we know is that the current crop of diesel-hybrids cannot even match a Prius HEV in CO2 emissions on the NEDC.

But they are considerably more expensive. Toyota would be foolish to consider that approach, and Toyota is far from foolish.

 

We also know all the objections here that a Diesel could not work in hybrid have been proven wrong.

I'd imagine all the possible engineering solutions to getting the 2015 Prius to 60 mpg will be equally expensive.

Other than the odd bias by a few on PriusChat forum, a Diesel Prius getting 60 mpg would be a great car.

 

Enjoy your fantasy. Everybody else with a tiny bit of hybrid history knowledge knows that diesel-hybrid concept cars were on the road some 15 years ago, courtesy of the PNGV program. I'll say it again: the objection to diesel as the ICE was not technical, it is an understanding that the advantages are minor and easily outweigh the disadvantages compared to petrol hybrid.

Not a chance. Toyota pursues near term R&D it can sell to the mass market.

It would be a market flop if it cost $5k more than a Prius HEV, let alone $10k.

 

1. every hybrid car needs ICE that gets "good" efficiency from lets say 10 kW to 40 kW. Rpm in case of PSD doesn't really matter.
2. Current Turbo charged Diesel engines are tuned to get very good torque at low rpm (high power at low rpm), in Peugeot case this is 300 Nm at 1750 rpm, that is already 54 kW at 1750 rpm. BSFC of any engine is almost at full load, so 42% efficiency of that engine would be way higher than 10 kW. Peugeot doesn't use PSD for gearbox, in the front of the car is a normal e-HDI (start/stop) unit, with a little bigger (8 kW) belt driven generator, (A/C is also belt driven), and normal automated manual gearbox. Complete electric drive is in the back of the car, it's just a simple add on to a normal e-HDI, much like the Plug-In Hybrid Retrofit Kit without charging capability and not in wheel el. motors.

If Peugeot used 1.6 e-HDI that would be a real MPG killer, but the price premium, considering a normal small diesel engine is already in the price range of Yaris hybrid would be just too much. So they chose to make it 200 hp AWD car that justifies a price premium, but doesn't get as good fuel efficiency as Prius.

If you put all that effort to a petrol engine you can also get to same thermal efficiency (DiesOtto maybe), but the price premium can be too hard and MPG number would be still 10% lover than diesel, because of fuel energy content.

 

Have you ever bothered looking up EPA air pollution scores of "clean diesels" at Compare Cars Side-by-Side or http://www.epa.gov/greenvehicles/Index.do?

Here's an example: Compare Side-by-Side. Select Energy and Environment then select California for the state. Notice the 6/10 vs. 9/10 for EPA smog score? Also notice the MUCH higher CO2 emissions per mile (which has nothing to do w/the earlier score)?

See How much carbon dioxide is produced by burning gasoline and diesel fuel? - FAQ - U.S. Energy Information Administration (EIA). CO2 emissions for a given amount of diesel are considerably higher than the same amount of gasoline.

 

And from the UK cost of the PIP I can buy two Auris (Euro Corolla) or one and a half normal Prii. Even at our high petrol prices I'd have to think hard.

 

We don't have PIP yet... so no problem . But I park on the public road without any electrical outlet nearby so PIP for me is useless. I'm looking for a good price for 2013 Auris Hybrid. I hope it will be priced as good as Yaris Hybrid.
In my opinion Toyota would go with high efficiency petrol engine, probably with DI, better battery (Li-Ion?), more effective regen braking and workout thermals in cold weather conditions (last step not important in current emission cycle tests). They probably add shorter init cycle from PriusC/Yaris HSD which allows engine to work in S0 state to gain a bit of efficiency during short trips.
I'm not sure if Valvematic (available in 1.6 petrol Auris) is the way to go. Hybrid doesn't need that. VVT-i allows it to switch for high power in high rpm or stay efficient in low RPM. That is all we need from hybrid engine.
Cylinder switching is a nice idea, but on the other hand Yaris does everything it can do to turn off the engine at all under low speed, while higher speeds need ICE on all the time so this seems to be useless.

 

But it's a bigger vehicle. And when does price ever come into the argument when in favour of the Prius over a Corolla or other smaller car? We always argue that we drive the car we want, and not just for the fuel economy savings, yet change our argument when it suits. We can't have it both ways. The 3008 is bigger and thus a different car. We're comparing apples and oranges or a Prius C and a Prius.

And the Peugeot 508 sedan and station wagon diesel hybrid gets similar performance figures to the 3008 but does 78.5 mpg compared to the Prius 72.4. Peugeot 508 HYbrid4!

Sure it's more expensive, but then the Prius is more than the Yaris hybrid here. The SW also looks pretty mean

 

So? You said: "Pretty much swapping out the current gas engine for a modern turbo Diesel would get the Prius to 60 mpg."
And Peugeot and Volvo don't work like the Prius. I repeat, this is much more complicated than you think.

 

As much I seem to disagree w/ProximalSuns on many things, I don't think his assertion is that far fetched.

Let's assume there are no emissions issues (we'll let it be as "clean" as current "clean diesels") and price isn't a concern. It seems reasonable if you compare gasoline vs. diesels versions of the same car on the EPA test and in some "real world" driving tests. Dig some up on Compare Cars Side-by-Side.

 

How about this one: Lets compare 3rd gen Prius with Peugeot 3008 Hybrid4 in the real world:

Prius, from model year 2011: Overview: Toyota - Prius - Spritmonitor.de
Average fuel consumption (US fuel economy): 4,95 l/100 km (47,51 US MPG)

Peugeot 3008 Hybrid4: Overview: Peugeot - 3008 - Spritmonitor.de
Average fuel consumption (US fuel economy): 6,12 l/100 km (38,43 US MPG)

If you take into account the volumetric energy difference between gasoline and diesel fuel, the o'mighty carcinogenic diesel hybrid looks even worse: ~6,79 l/100 km (34,64 US MPG) gasoline equvivalent.

It doesn't matter how you slice it, diesel hybrid is dead.

 

There is also Peugeot 508 hybrid 4:

Übersicht: Peugeot - 508 - Spritmonitor.de

But you must know that it produces 200 HP and it also has higher ground clearance. But my point is that you can also make $ 5.000 more expensive Prius with high tech (maybe diesel) technology gasoline ICE and beat that consumption and power.

 

Is someone doesn't think the Prius - 3008 Hybrid4 comparison is fair, we can take Prius + (Prius V) as well:

Prius + /Prius V/: Overview: Toyota - Prius Plus - Spritmonitor.de
Average fuel consumption (US fuel economy): 5,49 l/100 km (42,84 US MPG)

 

I'm very well aware of that. Camry hybrid delivers exactly 200 HP as well: Toyota Camry MPG Reports | Fuelly
40 car average on Fuelly in 2012 is 39,4 US MPG.
Same story, diesel hybrid is dead.

 

Tell this to Europe, where diesel is effectively 24 % cheaper if you compare energy content. General public believes that diesel is the future, because of this artificial (tax) price difference.

Ok some Europe countries have the same price of diesel and gasoline but the energy content is still 10 % in favor of diesel.

 

I don't have to tell this anyone in Europe because that false tax difference is about to change. EU wants to tax fuels based on energy content. If this happens diesel will be more dead.
Anyway I don't think general public believes that diesel is the future, only the uneducated/brainwashed ones. I believe the future might be very dark, but not so dark.

 

this discussion is a bit in the weeds since MPG is just an arbitrary point of reference. I think what most consumers are interested in would be the lowest cost of operation per mile, followed shortly by the lowest cost per passenger mile. some consumers will be interested in the emissions, perhaps only because they wish to get an HOV sticker for an SOV and cut down on their commute time.

the street price of diesel versus gasoline is more of a function of regulatory actions and taxes than it is of production costs and btu content, in effect making the choice between diesel and gasoline a political decision rather than a consumer or vehicle manufacturer decision.

when the discussion migrates to cost of operation, I think PHEV will shine for most.

 

I can't think of a single person I know, who cares about cost per passenger mile. There are people who care about max occupants, but that is a different issue. No one is changing their number of passengers based on fuel economy.

Most consumers are interested in how cool it looks.

 

You don't know anyone that commutes on a motorcycle, bicycle, scooter, or other SOV?

 

$5000 more for Prius just to increase mpg from 50 to 60 (4.7 to 3.9 l/100km) is insane. For that money one can buy 2300 litres of unleaded Pb95 fuel, which means that to see savings you have to drive over 255 000 km / 160 000 mi just to compensate higher price of the engine. If you add higher cost of service (oil, particulate filters, maybe AdBlue) it is just not worth it.