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A Porsche Hybrid? Does That Make Sense?

By - Source: Tom's Hardware US | B 0 comment

Chicago (IL) - 'Hybrid' has become a very political term these days: Whether you like it or not and whether it is true or not, it implies low gas consumption, reduction of green house gases and clean(er) air. Most car manufacturers are playing with car concepts, but seriously, would you buy a hybrid Porsche? We caught up with the company to find out if this concept makes sense - and provide background how the Porsche hybrid will work.

If you visited the most recent Porsche press conference, held at the Chicago Auto Show, and you have some knowledge about the company and its products, there were few surprises. Movies about its racing heritage and current successes and a new car: The Cayenne GTS SUV with a 405 hp, 4.8l V8 engine that propels the 5000-pound car from 0-60 mph in 5.7 seconds and a top speed of about 160 mph. It isn't a great fit for our time from the view of green house gas emissions, but it is what you expect from a Porsche: There's a certain engine power, acceleration capability and exhaust note that you would be looking for in a Porsche.

Somewhere in the middle of the presentation, Porsche reminded journalists that the Cayenne hybrid is in development. The company's hybrid idea isn't exactly new. Porsche announced its intention to bring a hybrid SUV to market back in 2005 and since early January we know that the company will also offer such a drivetrain for the upcoming Panamera sedan. The fact that neither car was in Chicago and there wasn't anything particularly new about the hybrid, almost sounded like an excuse for the gas-guzzling Cayenne GTS.

In some way, hybrid in its original sense (we'll leave the ill-fated idea of a 270 hp Honda Accord hybrid out of consideration here) in some way contradicts the idea of the Porsche and its characteristics, right? Or can a sports car run on a hybrid engine and still retain its image of a sports car? Let's have a closer look.

There aren't many specs of the hybrid engine available today. What we know is that it is likely to use the current base engine, a 3.6l V6 with 290 hp, and an electric motor with about 46 hp. On the performance side, this car will deliver substantially more torque than the regular V6: Porsche promises about 400 lb-ft at 1800 rpm for the hybrid, which compares to 273 lb-ft for the 290 hp V6. The company also says that the hybrid will be able to tow up to 7000 pounds - the same as other Cayennes.

At the same time, Porsche promises that the hybrid will improve fuel economy over the standard Cayenne by about 30% (that is up from a 20% estimate in 2006 and up from a 15% estimate in 2005), which indicates that the car should end up somewhere in the range of 17-19 mpg in the city and somewhere between 24-27 mpg on the highway. Early Cayenne hybrid prototypes hit 24.4 mpg in the US FTP cycle, compares to 17.9 mpg for the standard V6.

These numbers, however, provide little insight in the true characteristics of the car as well as what a typical Porsche customer Cayenne hybrid buyer can expect from this car. In the end, if you want those fuel savings, you will have to drive the car much like a Toyota Prius and not like a Porsche. So, will this be a performance-focused or a fuel-economy-focused vehicle? Porsche spokesman Dave Engelman as well as vice president of marketing David Pryor gave us a few more details on how this car will fit into the company's product line and why the company believes Porsche buyers will purchase this SUV.

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"A Porsche hybrid will have to retain all of the driving characteristics Porsche is known for"

TG Daily: Hybrid cars are not exactly racecars today. How does a hybrid model fit into a family of sport scars?
Engelman: The beautiful part of a hybrid is that if you drive it easy you will get all the economy a hybrid can offer. You will get a V6 engine that will shut off at a traffic light, an engine will shut off in [standing] traffic and not restart again until you demand it by the accelerator or when you reach a certain speed, something like 35 or 40 mph, or to recharge the batteries. Also the air conditioning runs of the battery and the power steering is electric. All the accessories that normally would run off the engine are now run by the electric motor. This in itself results in about a 1-2% increase in fuel economy. For the performance side of the hybrid, you have the V6 gasoline engine plus the electric engine. As a result, you'll see the most benefit of the hybrid when driving around town, where saving will be around 30%. On the highway, the fuel economy will not be much better than in a standard car.

TG Daily: That sounds though, as if that will be a different kind of car and not really a Porsche.
Engelman: A Porsche hybrid will have to retain all of the driving characteristics Porsche is known for - great handling, performance, dynamic feedback to the driver. All of the things that makes a Porsche a Porsche. Look at the 30% increase in fuel economy, that is a fantastic result and we expect our hybrids to still drive like a Porsche.

TG Daily: Hybrid sounds a lot like marketing today and, for Porsche, more like an alibi.
Pryor: There are many cheaper ways to accomplish that goal. When you are looking at how much money we are investing in the hybrid, then you see that it is not just a marketing exercise. Every automaker has to be raising the bar. In the U.S. there is the 35 mpg standard that is coming, in Europe it is 130 grams [of CO2 emissions]. We all have to adjust to it. We all have to start doing the research now and find out how we get there. Hybrid technology is one solution.

TG Daily: Porsche first demonstrated the Cayenne hybrid on a day when Greenpeace protested against the high gas consumption of Porsche vehicles in front of the firm's headquarters, not knowing that a hybrid was shown in the back. But the hybrid may not be enough to convince groups such as Greenpeace.
Engelman: We followed all those reactions from environmental groups. In the end, yes, one hybrid [for now] may not make much of a difference when you look at the amount of cars that Porsche sells. But they all appreciate that Porsche cares - and bring such a car to the market.

TG Daily: From Porsche's view, what is the state of hybrid technology today?
Pryor: Hybrid is technology that works now. It is a proven technology that is further developed every day. As the technology improves the mileage and power will get better. The market is trying to figure out how we address this environmental issue and no one knows whether it will be hybrid, diesel, biofuels, or hydrogen in the end.

TG Daily: So, the hybrid vehicle could simply be a transition?
Engelman: Hard to say. Well, as said, it works now. Fuel cells are running around, but the question is really whether they are affordable. Sure, there are technologies out there, but they are not as efficient as gasoline when you look at the performance they deliver. Porsche engineers work on the hybrid concept to bring the performance back - so when you buy the hybrid you get the braking capability, the handling capability and the acceleration capability of a Porsche.

TG Daily: Do Porsche buyers care about gas consumption?
Engelman: They do. They may not care as much in terms of what the cost per gallon is, they certainly care about the environment.
Pryor: They want to buy a product from a company that also cares about the environment. Which product they may choose in the end may or may not be environmentally friendly, but it is important for them to have that association with a brand that is doing something for the environment - like the hybrid.

TG Daily: We have heard earlier about what you call Porsche DNA. Lowering the gas consumption isn't part of that. Do Porsche customers care more about the performance of their car or about the environment?
Engelman: Our customers, both of sports cars and Cayenne, care about performance first. But our sports cars are inherently among the most efficient to begin with.

TG Daily: There are some fantastic diesels on the road today and companies such as Audi and BMW have proven that diesels can be sporty cars. Is a diesel in Porsche's future?
Engelman: No. Well, never say never. Diesels and Porsche has never been a combination that has been attractive to Porsche. Diesel is not something Porsche is interested in at the moment.

TG Daily: On the other side, there are pure electric cars such as the Tesla roadster and the upcoming Fisker Karma. Can you imagine a Porsche with just an electric engine?
Engelman: Without a stereo that plays the exhaust sound of a 911? Seriously, this is important and in those cars you don't get that. But again, the future is the future.

TG Daily: ... which means that there has to be enough room for enhancements in the traditional gasoline-powered engine?
Engelman: There is definitely room for more improvements. We currently have direct fuel injection (DFI) on all four of our Cayenne engines, and it will be employed in the next generation 911 and Boxster as well. Second generation Direct Fuel Injection with different combustion modes, displacement downsizing and turbo-charging also are avenues that will be pursued. New systems are in development to eliminate the conventional camshaft and valve actuation along with the electrification of pumps and actuators - to only use them when needed for applications such as power steering and the water pump.

TG Daily: Thank you for the interview.

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How the Porsche hybrid system will work

Porsche's hybrid drivetrain will be a full-hybrid, as opposed to a "mild hybrid", which simply offers advanced starter motors to turn the engine off when the car is coasting or being stopped (and back on under acceleration). Media reports claim that the Cayenne hybrid will be able to hit 75 mph running on the battery alone, which is questionable, if we consider the 46 hp electric motor and 300 extra pounds due to the hybrid parts. Engelman's estimate of 35 - 40 mph seems much more credible.

The hybrid module consisting of the clutch and electric motor is located between the regular 3.6l V6 combustion engine and the transmission, which Porsche found to be the best combination of fuel-efficient and acceleration for the Cayenne. The functions of the gas engine and the electric motor as well as the resources of the battery (located in the trunk in the spare wheel well) are coordinated by the "Hybrid Manager", which easily the most impressive technical detail of Porsche's hybrid technology.

Placed in the engine compartment, the Hybrid Manager oversees about 20,000 data parameters at any given time, compared to about 6000 in a regular engine. It is directly connected to power electronics that control the flow of electric current between the battery and the electric motor as well as a spindle actuator that controls the "disengagement clutch" (and replaces and otherwise needed starter motor) between the combustion engine and the electric motor.

The power source is a battery pack based on nickel-metal technology - similar to that in a Toyota Prius, but about twice in size. However, we hear that Porsche is also working on a lithium-ion version of the battery module. There is no plug-in capability at this time, which means that the battery is charged through the motor while the car is braking and accelerating. And apparently, this feature will allow drivers to almost exclusively use the motor brake in "smooth" city driving - instead of the regular brake discs.

As mentioned by Porsche earlier, there are other unique electric features in the Cayenne that are designed to save gas. Components such as the electro-hydraulic steering and vacuum pump for the brakes as well as the air conditioning run on electric power, contributing about 1-2% in gas savings (of the 30% overall).

Conclusion

Of course, there isn't much of a conclusion until we actually see the hybrid on the road. From a perspective of the environment, a V6 hybrid with potentially more than 300 hp may not make much sense. Realistically a rating of 19/27 mpg is still far off from what we expect "greener" vehicles to achieve. But it certainly is an improvement over the gas-guzzling monsters we have on the road today and certainly an improvement over Chevrolet's mindset to combine a hybrid with a 6.0l V8 engine. Hybrids today appear to be a playground for manufacturers to climb the learning curve, which hopefully will bring us those 35 mpg and 40 mpg SUVs many U.S. seemingly are waiting for.

The unknown variable especially for companies such as Porsche is what potential buyers are looking for in a Porsche hybrid. The good news is that the price premium won't matter much - a company that anyway isn't really known for cheap cars can tack on several thousand dollars and customers won't complain. The more important question will be whether customers will accept those wimpy 17" wheels (of the hybrid prototype), the less-engaging electro-hydraulic steering, and the V6 engine sound for a price that could end up in the range of the V8 Cayennes.

Lexus proved that luxury hybrids in fact work and attract huge numbers of buyers, virtually in all luxury price segments. Even at the very high-end, Lexus is said to be selling more than 2000 LS600h limousines per month. These cars have a starting price of about $104,000.

Porsche is expected to launch its Cayenne hybrid in 2009 or 2010.

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