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HyBoost concept achieving close to Prius-level CO2 emissions; aggressive downsizing with advanced boosting and micro-hybrid system

HyBoost offers comparable performance to the conventional current 2.0L variant but with fuel economy of a strong hybrid. Click to enlarge.

The HyBoost demonstrator being developed by Ricardo and its partners (earlier post) is achieving comparable performance to the conventional 2.0L version of its vehicle (a 2009 Ford Focus) but with fuel economy and CO2 emissions approaching those of a Prius, according to David Boggs, Ricardo Technical Specialist, Engines, in a presentation at the recent 2011 Directions in Engine-Efficiency and Emissions Research Conference (DEER) hosted by the Department of Energy in Detroit.

HyBoost achieves this by combining aggressive 50% downsizing of the engine with an electric supercharger for transient low-speed performance, and a micro-hybrid stop-start and energy recuperation systems, Boggs said.

Downsizing the 2.0-liter base engine to a 1-liter, boosted direct injection (EcoBoost) engine delivers up to a 25% reduction. The stop-start system with 6 kW of regenerative braking capability delivers another 10%. Cooled EGR, revised turbo match and the e-boost at the low end provides another 6% reduction, while the use of taller gears and a gearshift advisor chips in another 7% reduction. The HyBoost demonstrator comes in at around 99 g CO2/km but with further system optimization, Boggs said, they can get it down to around 89—the same rating as the Prius.

Click to enlarge.
Ricardo’s gasoline engine roadmap focuses on CO2 reduction through downsizing and the use of synergistic technologies. Click to enlarge.

Engine downsizing is central to Ricardo’s gasoline engine roadmap for future CO2 and fuel economy improvements. Next-generation spray guided direct injection combustion systems support aggressive engine downsizing with robust stratified engine operation having excellent fuel consumption. A highly tolerant combustion system and knock mitigation are necessary to achieve the very high BMEP levels. The HyBoost vehicle demonstrates the potential to achieve CO2 reduction significantly with cost-effective technologies...the application of synergistic technologies enables high levels of engine downsizing and vehicle fuel economy improvement.

—David Boggs

Micro-hybrid market. According to a recent report from Pike Research, sales of vehicles equipped with stop-start systems—one of the synergistic technologies highlighted in the HyBoost concept—will grow rapidly in the coming decade, rising from 3 million units in 2011 to 37.3 million units per year by 2020. By the end of the decade, a total of 186 million vehicles globally will incorporate the technology, which will become standard on the majority of vehicles sold in Europe as well as on dozens of models in North America and Asia, according to the Pike report.

Requiring more robust batteries and starter systems than are found in conventional internal combustion engine (ICE) vehicles, and priced at a small premium over ICEs, stop-start vehicles (SSVs) are considerably less expensive than hybrid electric vehicles (HEVs).

By 2020, stop-start vehicles will represent more than one-third of all light-duty vehicle sales. SSVs are already outselling hybrids globally by a factor of 3.5 to 1, and that gap will widen to a 16 to 1 ratio by 2017 because of the lower cost of SSVs compared to HEVs.

—Pike research director John Gartner

Due to stringent emissions regulations, the largest SSV market for the forecast period (to 2020) will be Western Europe, which will represent 98% of the 3 million SSVs sold in 2011. By 2020, Western Europe will account for 42% of all SSVs sold. The fastest-growing region for SSV sales will be North America, where annual sales will roughly double each year from 2011 through 2020, according to Pike. More than two dozen SSV models were available in Western Europe as of early 2011, while in the United States, only three SSV models are for sale.



Roger Pham



Basically, since most, if not all, components required for electrified vehicles can be manufactured at much lower cost in Asia, should one conclude that Asia will drive e-vehicles, EU will drive diesels, N-A and Australia will drive heavy Hummer like V-8? Fortunately, it will not happen exactly like that. Made in Asia lower cost e-vehicle components will be distributed world wide for local assembly lines and to get around higher import duties on assembled products. That is already going on with ICE vehicles but it will be more so with future e-vehicles.

After that (i.e. when the battery is exhausted), you have to pay yourself.
Taxi operators have run many Priuses longer than I have ever owned a car, including cars I have sold to scrapyards, without exhausting the battery. How is this likely to be a problem for me, and wouldn't an extended warranty on the battery be cheap insurance? Given the very low failure rate of these batteries, insurance could be sold for cheap and still be profitable.

Consult EPA. The emission legislation says mileage or age; which comes first.

In Sweden, most Prius cars are company cars or taxis. Very few private owners even consider a Prius. If they want an alternative to gasoline, they buy E85 or diesel (~60 % of the market) cars. Company cars are changed every 3 (2-4) years and usually have a much higher than average mileage after this period. Taxis have even higher mileage. However, batteries seldom break during this period. It is a problem on the second hand market. Consequently, you can get a 5-year old Prius pretty cheap. Maybe this explains the problem. This is how the market handles the problem. I doubt that changing batteries in a high-mileage 5-year old Prius would double its value.

Why is Prius popular as a company car? Well, it is due to incentives. First, the company pays the premium cost for purchase, not the user. Second, the tax the user has to pay is based on a similar conventional car (which is much cheaper, as said above). Third, this tax is reduced by 40 % compared to the conventional car. Now, this taxation scheme is about to change, i.e. the 40 % reduction will be cancelled. The result will inevitably be a dramatic drop in sales of hybrid cars. The apparent success of Prius in Sweden has been based on economic incentives; not its own merits.


Once you adjust for features and option the Prius hybrid premium is about $1500.. unfortunately Toyota piles up the options on these cars.


GM still makes many 4-cyl cars with guaranteed progeria for those who do not want to keep a vehicle over the basic warranty period.


Prius is not available with a conventional drivetrain. Let's compare different versions of the Auris instead. I did adjust for the features and options for each model. The price difference is substantial! In light of this, the HyBoost concept looks even better.


Yes, the Auris with a bog-standard engine is much cheaper than the Hybrid version. Same for the most basic Focus compared to a Prius.

The point is that once you add an 'ecoboost' engine with turbocharging, high compression ratio, etc, you end up with a car which isn't that much cheaper than a Prius (look at how much the current ecoboost focus model costs). The 'eco' version of any car range always seems to be a few thousand pounds more expensive.

Diesels, on the other hand, seem like a pretty good deal.

Taxis have even higher mileage. However, batteries seldom break during this period. It is a problem on the second hand market. Consequently, you can get a 5-year old Prius pretty cheap.
Not in the USA. Kelly Blue Book states "The Prius has historically retained an above-average resale value regardless of fluctuating gas prices, and we expect the 2011 to be no exception."

Nickel-hydrogen batteries were preferred for satellites because of their long lifespan. And again, Prius batteries are common enough on eBay from wrecks that obtaining a replacement is no difficulty.

Care and feeding of turbochargers in highly-boosted engines is an issue too (I know from experience). Just because the purchase price and fuel cost of HyBoost is competitive does not mean the life-cycle cost will be. Regardless, any improvement is just that, and anything which bypasses supply-chain limits of hybrids is an improvement.


My wife is changing her old Camry for a 2012, 50+ mpg Prius III. With gas @ $5.20/gal and rising regularly, it seems to be a wise decision. The new 2012 Camry Hybrid (41 mpg) is also an interesting interim solution.

Both Hybrids will certainly give trouble free service for at least 10 years. Since gas price could be as high as $7 to $8/gal during the next 10 years, high quality efficient hybrids may be one of the best solution, until extended range BEVs are available.


So, taxis do not have high mileage in the USA??? I simply do not believe that. In Sweden, the EU in-use durability limit can be covered in 1-2 years of use as a taxi cab and the cars are sold after this period, so the risk of battery failure is purely assumed by the second customer. Nevertheless, I have noted that Prius is a very popular as taxi cab in Sweden. However, I would never buy such a Prius as a used car. Maybe another difference compared to USA is that the median car life in Sweden is ~15 years. Prius, as any other Japanese car, is made to last the 8 years a car is supposed to live in Japan (cars are exported outside Japan after that).

If you think that the turbocharger is a problem in highly boosted engines, you should also note the countermeasures they have taken. For example, this engine use cooled EGR and water cooled manifold. In fact, it is even possible to get as low exhaust temperature as a conventional naturally aspirated engine. Regarding mechanical load, the maximum cylinder pressure is of course higher than for a naturally-aspirated engine. However, it is still far lower that for a diesel engine that has similar BMEP. The technology to make such an engine structure is well-known. Would this increase engine weight? Well, the weight penalty for a 2-liter diesel engine compared to a naturally-aspirated gasoline engine can be as low as 10 kg (al engine blocks in both cases). Whether you like it or not downsized and highly turbocharged engines will rule in the future. Even Toyota is considering this for future Prius cars.


Once again I must repeat: one of the most important objectives of HyBoost was to reduce the cost. This is because they concluded that the Prius drivetrain is too expensive. If increased market penetration of hybrids is an objective, the cost issue must be addressed.

All of you who seem to hate the HyBoost concept and favor the Prius, could you explain the advantages of the Prius hybrid system to me? Don´t you think that a rapid introduction of concepts as this would help the introduction of hybrids? Or is it just so that you want to express a different opinion no matter what I say?

taxis do not have high mileage in the USA??? I simply do not believe that.
Go back and look at what I quoted from Kelly Blue Book. It says what it says about resale value. It says nothing about taxis. Most taxis in the USA are cars like the Ford Crown Victoria. The only Priuses in taxi service in N. America that I've heard of are in Vancouver, British Columbia, CANADA (not the USA).
All of you who seem to hate the HyBoost concept and favor the Prius, could you explain the advantages of the Prius hybrid system to me?
I don't hate Hyboost. You're mistaking skepticism about durability (from personal experience) for opposition. There is also the lack of other economies, such as reduced brake usage and wear, to be considered. Something like a turbo Scuderi air hybrid addresses that detail, which HyBoost does not.

Time will tell.


AS always when I post something on this site, you have a different opinion. Maybe I should test this hypothesis some time by providing a comment with quite different opinion that I actually have (even if it is wrong), just to see if you object about that, too. In fact, will test that right now:

I agree with you that the HyBoost does not address reduced brake usage and wear (through regenerative braking, I presume), just as the turbo Scuderi air hybrid does.


If you make false generalizations about vehicles in different markets and types of service (resale value of USA personal vehicles vs. European taxicabs), I'd hope that somebody disagrees with you (and with me if/when I do it). On the other hand, I started out largely agreeing with you.

I would expect that any vehicle used in taxi service, hybrid or not, is fairly cheap on the used market. Cab companies watch the bottom line and wouldn't be selling a vehicle if it hadn't become expensive to operate. Given the fuel savings of the Prius, high expenses probably mean service items. I wouldn't pay much for such a vehicle either.

Do you agree that this is a very likely explanation for the difference between the KBB info for Prius resale value in the USA and your observations? (Next it'll be dogs and cats living together! Mass hysteria!)


No, I did not generalize. I specifically stated that it was the condition in Sweden.


In a search on the Web about Prius batteries, you get a lot of hits (>1M). Obviously many of those batteries break, or at least you can see a lot of concern from owners. As I explained, most Prius cars are used as Taxis and company cars in Sweden; Prius are not bought by private owners. In countries where the majority of the cars would be bought by private persons, the average mileage will be far lower and the battery life would not be such a big issue. I can agree with you on that.

Let me just conclude that the price of a lead-acid battery and a supercapacitor would be far lower that for the Prius battery pack. I would expect the supercap battery to last the life of the car, while the lead-acid battery would probably last as long as a conventional battery, i.e. 5-10 years. However, it would be very, very cheap to replace. I hope we could at least agree on that the HyBoost has an advantage here.


Peter, I shouldn't have to remind you of your own words, but you did say this:

When the NIMh battery is exhausted, the car is worth close to... nothing. Prius owners are then crying all the way to the bank.
On the contrary, a trivial search finds both used and rebuilt Prius battery packs from as low as USD1200 or so. Individual cells are available from many sellers, proving that the market for replacement batteries isn't enough to consume the supply. If a Prius owner has a battery die out of warranty, the cost of replacement is quite reasonable (and the resale value of a partially-functional battery may offset quite a bit of that).

The usage patterns and amount of wear and tear on a vehicle in taxi service vs. one privately owned cannot be directly compared, and neither can the resale values of the vehicles. I would not be surprised if you're correct about Prius usage and sale prices in Sweden (you've given no reference), but I would appreciate it if you would acknowledge that I have given you references for the USA which back my claims of the market here. You appear to be asserting that your PhD makes you an authority on everything, which is absurd.

I have no disagreement with your 12:21 AM statement above. I also agree that the HyBoost has purchase cost and supply-chain advantages over vehicles like the Prius, and I'd like to see lots and lots of them on the market.


Prius batteries have proven extremely durable in the US.. Toyota says they have only replaced 1-2 under warranty in the 10 years it has been in the US (I dont believe it). I Prius Chat forum members say around 200-300k miles of life for those batteries. Honda's batteries have done much much worse.

We dont have Auris in the US, but I did a comparison between a Toyota Matrix and all the Prius models (2011) using the True Delta web site, matching all options and features. The Prius 1 has a hybrid premium of $692, the Prius 2 is $883 higher, the Prius 3 is $1156 and the 4 is $2117 higher.. I know Priuses are very expensive in Europe but in the US they are very well priced.. and could be much lower if manufactured here.

Toyota has managed to bring the cost of the hybrid premium very low..

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