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Of course, for starters there's a plainly obvious mathematical attraction to hybrid vehicles. In a 35-mpg CAFE world, selling four milquetoast earth-hugging nine-second-0-60-mph Malibu Hybrids allows the sale of one fire-breathing 3.3-second Corvette ZR1 without incurring any fines for Chevrolet.

That magic ratio will certainly be even lower for plug-ins like the Chevy Volt and Cadillac Converj concept, although we won't be able to do the math on those cars until NHTSA and the EPA figure out exactly how they're going to test them (and I'm eager for them to announce some sort of plan so the shade-tree plug-in hybrid fringe players can stop advertising these wild 200-plus-mpg claims that get the hoi paloi so riled up.

Okay that first point was kind of a cynical cheat, because the hybrids themselves don't directly engage the enthusiast, though I suppose it's fair to interject here that great looking, dynamic designs like the Cadillac Converj will draw enthusiasts no matter what's under the hood. And as cars like this, and the Fisker Karma (if it ever actually materializes, which I'm not overly confident of), and even the Tesla are getting the word out that an electric drivetrain doesn't have to deliver golf-cart/sensible shoes driving. And the range-extended electric concept certainly opens the door to a much wider range of auxiliary power units. I fully expect to see a turbine-powered generator serving as the range extender in one of these vehicles soon, as that solution is arguably better suited to the task than a reciprocating piston engine, and turbines can be made to run on a variety of alternative fuels. And a jet-powered hybrid certainly sounds sexy, no?

The automotive aftermarket primarily exists to serve the enthusiast, and if this past year's SEMA show in Las Vegas was any indication, the players in this $37-billion business foresee a market for green gear-heads. This year an entire section of the show was devoted to "Making Green Cool." A123Systems was on-hand showing off its Hymotion kit that converts any 2004-2009 Prius into a plug-in hybrid. At the heart of this kit is a 5kW-hour L5 Nanophosphate lithium-ion battery pack weighing 187 pounds. It mounts in about three hours, with everything fitting beneath the trunk floor in the spare tire well. The system plugs into the Toyota's power grid with no modifications to the stock controller. Because of the way the Hybrid Synergy Drive planetary transmission works, the engine simply must be used at certain vehicle speeds, and most regenerated energy goes back into the stock nickel-metal-hydride battery, but the plug-in battery gradually discharges, increasing the amount of time the car can operate at low speeds in electric mode. It recharges in about five hours when plugged into a conventional 115-volt outlet. Priced at about ten grand installed (plus shipping), buyers get more in the way of bragging rights than they do future economic benefit, but I suppose the same can probably be said of many of the products featured at SEMA.

The much more enthusiast-oriented gas/electric SEMA star was Braille Battery's Nissan Altima Hot Rod Hybrid (also pictured at top). Developed and built in conjunction with Universal Technical Institute, its 2.5-liter four-cylinder is tuned to run on E85 gasohol and gets an electric-powered Vortech supercharger that ups combustion output to about 270 horses. The traction motor is also juiced up to produce a reported 440 total-system horsepower. A reworked suspension and fat 40-series low-rolling-resistance Yokohama tires supposedly provide 1.02g lateral grip and quarter-mile acceleration times of 12.9 seconds at 109.2 mph. Its roof is also covered in solar panels, though it's hard to imagine that they could really pay off in extended range or added power even when circulating a high-desert track like California's Willow Springs. (Now that I think of it, I wouldn't be surprised if decals that look like solar-panels didn't become the woodgrain or faux carbon fiber of the hybrid-geek future.) And what about gas mileage? The fuel tank will reportedly last for 35 laps of the 3.7-mile race circuit in Sebring, Florida, as compared with only 20 in a conventional non-hybrid Altima race car. We'll find out how well this hybrid hardware performs when the Hot Rod Hybrid competes in a newly formed Hybrid/electric class of this season's Redline Time Attack series of road-racing-circuit time-trials. It'll also be entered in April's Cannonball Run/One-Lap of America race (with Motor Trend as this year's media parther).

The final SEMA hybrid I'll mention is the RENNtech Mercedes GLK Pikes Peak Hybrid SUV. This entry also gets a souped-up combustion engine (computer upgrades, exhaust headers, new heads and cams), to which is added a mild-hybrid motor/alternator, not unlike those used in the Chevy Malibu/Saturn Aura Hybrids. This bolt-on unit supposedly adds up to 40 pound-feet of twist to the engine, drawing from a motor-generator and a 72-volt battery pack. The SEMA show car used six Optima 12-volt spiral-wound lead-acid batteries located in the spare-tire well, but a nickel-metal-hydride pack capable of being recharged during regenerative braking will be developed before this concept makes its official debut in the exhibition class at the 87th Annual Pikes Peak International Hill Climb this July.

And while the Redline Time Attack, One Lap, and an exhibition class at Pikes Peak may not draw very much attention, these last two examples are charging down a direct path to the enthusiast's heart: motorsports. Of course, throughout the automotive age, racing has driven such automotive innovations as disc brakes, fuel injection and countless other advances in automotive performance, efficiency, and safety. Nobody knows this better than the SAE, which organized a Green Racing Committee whose task it was to develop a set of Recommended Green Racing Protocols, which was just published last October. SAE started by holding a number of technical forums to gather input on the topic from manufacturers, motorsports sanctioning bodies, race teams, etc. Then a working group comprised of representatives of the EPA, the Department of Energy, Argonne National Labs, the American LeMans Series (ALMS) and its sanctioning body, the International Motor Sports Association, set about drafting the protocols.

The protocols are based on five elements:

1. Use of renewable fuels;
2. Use of different engines, fuels, and propulsion systems in the same race;
3. Recovery and reuse of braking energy;
4. Regulation of performance by energy allocations, not detailed hardware specs
5. Use of exhaust pollution control strategies and systems.

The Green Challenge ranking system takes into account the amount of energy each car uses, the greenhouse gases it produces and the fossil fuels consumed-on a well-to-wheels basis (calculated using Argonne's well known GREET analysis). These ranking factors are compiled into a single weighted number representing the car's environmental performance. The first race to include a Green Racing class was the ALMS Petite LeMans race, a 1000-mile high-speed endurance race run on the 2.5-mile Road Atlanta circuit on October 4, 2008. Included in the nearly 40 entries were conventional gasoline engines, direct injection gasoline engines, diesel engines, and-yes-hybrid assist technology. Fuels used include gasoline with 10% ethanol (E10), E85 ethanol made using cellulosic processes, and ultra-low sulfur diesel with a portion of synthetic diesel made from a gas-to-liquid process.

The Corsa Motorsports/Zytek LMP1 Hybrid entry is based on a Zytek 07S carbon fiber/aluminum monocoque chassis and powered by an ethanol-fueled 4.5-liter 32-valve Zytek V-8 producing 625 horsepower and a proprietary Zytek direct-drive electric motor energized by a lithium-ion battery pack supplied by Continental AG of Germany. Unfortunately, teething problems with the inverter, battery, kinetic energy recovery system and attendant wiring, cooling and management systems required further development, and the Hybrid missed its first two potential races. It's still expected to appear on the 2009 grid. The winners of the Green Challenge at this year's Petite Le Mans included a lightweight E10-powered direct-injected Penske-Porsche in the prototype class, and a GM Racing Corvette burning cellulosic E85 in the GT class.

It's worth noting here that almost exactly 10 years prior to last October's Petite Le Mans race, another hybrid running a Zytek electric motor coupled to the transaxle of a Roush V-8 appeared. This Panoz Q9 LMP1 Spyder was affectionately nicknamed "Sparky." Then as now, the idea was that regenerative braking would save wear on the friction brakes while electric boost extended range between refueling stops. But because the weight of the 1998-era battery pack was so great, the car finished 12th overall and never competed again. Hopefully in the months to come we'll find out whether modern batteries and 2009 controller technology-not to mention Green Racing Protocols-can make the hybrid racer competitive.

Endurance racing is a great forum for technology development, but to tap into the serious money and engage a truly huge global fan base, you need to get Formula One racing involved. And that is scheduled to happen this season. Formula One's rules changes for 2009 are the most extensive in years. They're aimed largely at making the series more interesting to watch by encouraging more passing and by making the technology employed more relevant to the fans. A huge part of that is the admission this year of kinetic energy recovery systems, or KERS for short. Naturally, the official KERS regulations are fairly extensive and will be strictly enforced. There are way more, but here are a few highlights:

- Maximum power in and out of the system is 60kW (80.46 HP) as measured at the wheels. (This limit may rise over the years.)
- Max energy release per lap is 400kJ, or 6-2/3 seconds a lap at the 60kW rate
- No energy can be released below 62 mph
- Energy may only be stored while the car is moving on the track (there's no juicing up in the pits) AND when certain threshold conditions of throttle opening, brake pressure, and acceleration are met
- Release of the power must remain under the complete control of the driver and be scalable between 0% and 100% of the maximum driver demand
- The KERS must connect to the rear-wheel drivetrain (4WD may be allowed for 2011)

There are a squillion safety regs too, calling for status lights and system shutdown protocols, and the like, but there is wide latitude as to the method of energy storage. Almost anything goes that can meet the requirements, be it hydraulic, mechanical, electrical, compressed air, whatever. Hydraulic storage appears to be a non-starter, as 40 liters of oil would be required to store the allowable energy, and that's simply too heavy. Electric storage in batteries and/or ultracapacitors is the obvious approach that most teams appear to be working on, and they're finding it's not a simple matter of scaling up a Prius system by a factor of three. To date several of these teams are still grappling with some fairly serious safety concerns. A BMW-Sauber team mechanic sustained an electric shock while testing in Jerez Spain, and the Red Bull team reported a "smoke and fume" incident at its development center in the UK. Toyota engine boss Luca Marmorini told the German magazine Sport Bild that:

"All teams are having problems at the moment. Building a safe system is proving a difficult thing, and for 2009, time is running out."-Luca Marmorini, Team Toyota

Other German newspaper reports quote Mark Webber of the drivers' safety union saying:

"Some teams are having problems with the chemicals that are used for the batteries. It is important to us that it is safe, when we are driving at 300km/h, or in the event of a heavy accident." - Mark Webber, GPDA (drivers' safety union)

And Williams driver Nico Rosberg admitted that: "For the first few races (of 2009), no team will be on the grid with KERS." - Nico Rosberg, Team Williams driver

Rest assured that these hiccups will be overcome. But there is another system that really intrigues me. It's a mechanical energy storage device that stores energy as rotational inertia in a flywheel. Now, if any of you is an avid racing fan, you may be thinking of the last flywheel hybrid racecar that made headlines, Chrysler's Patriot. That Le Mans prototype was electrically powered, with energy coming from a turbine-generator running at nearly constant speeds, with surplus power (and braking energy) being used to spin up a flywheel large enough to supply supplemental power down the long Mulsanne Straight at the Le Mans circuit in France. Safely containing that gigantic flywheel proved impossible, and the project was shelved. But the maximum power permitted by F1 is so much lower that the concept is quite workable now.

Flybrid Systems in the UK is developing the flywheel, which is made of long-filament carbon fiber and high-strength steel. It's only 8 inches in diameter and about 4 inches wide, and it spins in a vacuum on special patented hermetic bearings (this is necessary, because at its top speed of 64,500 rpm, the rim velocity would be over mach 3, and the air-friction would be too great). The flywheel weighs about 11 pounds, 22 including the containment drum, bearings and so forth. Flybrid has crash-tested the unit, spinning it up to top speed and subjecting it to a 20g impact. The flywheel survived the crash still spinning and undamaged.

A planetary gearset reduces the speed by about 5:1, and then a centrifugal clutch connects the device to a toroidal continuously variable transmission that manages the ratio difference between the flywheel and the geared connection to the car's transaxle output shaft. Torotrak and Xtrac are responsible for this part of the technology. In race conditions the flywheel always spins at between 32,250 and 64,500 rpm, and can reportedly go from zero to full power storage in 50 milliseconds. The entire package is said to weigh just 53 poundsand it only needs half a cubic foot of packaging space. That's believed to be considerably less space and weight than the electric hybrid systems require, which gives teams more ballast weight to work with and leaves them free to put it where it can do the most good dynamically. Not only is it power-dense, Flybrid claims that by not having to convert energy from mechanical to electrical and back again, its in-and-out system efficiency should fall between 65-70 percent, as compared with 35-45 percent for an electrical system.

Flybrid claims the technology can easily be sized, tuned, and packaged for use on road cars and last May the company embarked on a Flywheel Hybrid System for Premium Vehicles project in conjunction with Jaguar. Who knows? Maybe mechanical hybrid systems will turn out to be the best solution for high-performance vehicles-either practically, or from a marketing perspective, if flywheel KERS systems start winning high-profile Formula One races around the globe and energizing the enthusiast base.

Recapping my things-to-do list for hybrid engineers to win enthusiast hearts and minds to the hybrid cause:

- Boost hybrid fuel economy as high as possible to offset the guzzler hotrods we love
- Optimize packaging and power-delivery efficiency to make cool vehicle designs like the Tesla, Fisker, and Caddy Converj possible
- Design some extra bandwidth into hybrid systems so the aftermarket can do some performance tuning
- Support Green Racing to the very best of your abilities, as this effort will inevitably feed back to all of the above.