When We Compared Four Hybrid Pioneers, One Left the Others Behind

[This story originally appeared in the May 2004 issue of MotorTrend with the headline "State of the Hybrid Union."] The first two full-fledged gas/electric hybrid cars available in the U.S. were nothing short of technological moonshots, so great was their departure from the established paradigms of carbuilding. We all marveled at the Honda Insight's slippery shape, exotic aluminum construction, and stratospheric EPA numbers.

Then we were dazzled by the Toyota Prius' multiple electric motors and video-game energy-flow displays. But once the initial astonishment subsided, we couldn't help but notice that these cars just weren't terribly satisfying to drive day in and day out.

The two-seat Insight was first to market in late 1999, and the Prius sedan arrived soon after. Each accelerated like an economy car from a decade earlier. They both rode on rock-hard high-efficiency tires that offered minimal grip and followed pavement grooves and ruts with a fundamentalist's zeal. Both cars often accelerated and braked in a jerky and nonlinear fashion as the electric motor's assistance phased in and out.

Their suspensions also were calibrated for high efficiency. Minimal front-caster angle and electric power-steering assist combined to stifle steering feedback, and the cars required constant correction to stay in a freeway lane. Worst of all, mere mortals, not just heavy-footed magazine testers—weren't achieving the lofty fuel-economy figures logged by the EPA.

Finally, most objective automotive analysts concurred that not even Enron's accountants could conjure black ink from the design, development, and manufacturing costs invested in these sub-$21,000 cars. Even in hindsight, our initial ennui seems warranted.

Fast forward five model years—and the hybrid landscape is poised to change dramatically. We're growing well beyond the "science experiment" category here. No longer will this technology be confined to puny, funny-looking econoboxes that require owners to sacrifice driveability or comfort on the altar of thrift and ecology. Rather, electric assist is about to take its place alongside supercharging and turbocharging as a means of efficiently boosting the performance of normal, high-volume vehicles while quietly elevating Corporate Average Fuel Economy (CAFE) statistics.

So now seemed like a good time to take a look at how far hybrids have progressed and where they're heading.

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Current State of the Fuel-Economy Art

Mainstream car and truck buyers have demonstrated no real enthusiasm for fuel-efficient vehicles, but our government thinks we need them, so it's raising the corporate average fuel-economy standards for light trucks from the current 20.7 mpg to 21.0 mpg for model year 2005,21.6 mpg for 2006, and 22.2 mpg for 2007. Car CAFE will remain at 27.5 mpg, at least for now. Higher-mileage vehicles are coming whether we want them or not.

Get an automotive engineer talking about fuel economy, and most will admit that, when designing a vehicle to meet certain size, weight, and performance targets, changing from a traditional gasoline engine to a smaller engine boosted by an electric assist motor and battery with regenerative recharging will net a fuel savings of about 25 percent. Switching instead from that original gas motor to a similarly powerful diesel engine also would save about 25 percent. In August 2002, we tested these claims of diesel and hybrid parity by sending a VW Jetta diesel along on a 250-mile mixed-driving loop with a like-sized Toyota Prius and Honda Civic Hybrid. Average fuel economy on the loop ranged from 39.4 mpg (Honda) to 42.3 mpg (VW), and acceleration to 60 mph varied from 12.7 seconds (Toyota) to 13.8 seconds (VW).

Of course, a diesel-powered hybrid would return even better fuel economy, but the diesel engine's future is in limbo in this country. Tough new emissions regulations threaten to outlaw light-vehicle diesels, barring a technological breakthrough that dramatically reduces emissions of particulates (soot) and NOx (oxides of nitrogen). These regs went into effect this year in states adhering to California's stan-dards, and they'll be phasing in nationwide by 2008, which is why more carmakers are looking to gasoline-powered hybrids to boost their CAFE numbers.

Toyota and Honda have blazed markedly different trails into this hybrid frontier. Honda's Integrated Motor Assist (IMA) system in the Insight and Civic Hybrid is mild and elegantly simple in its operation—an electric motor is sandwiched between the traditional engine and transmission-either a five-speed manual or a continuously variable transmission (CVT).

Fuel is saved by switching off the engine when stopped or coasting and by downsizing the engine and relying on the electric motor to assist with acceleration. The motor is powered by energy stored during deceleration and braking when the motor functions like a generator, recharging an onboard battery. (Today's hybrids are never plugged in for recharging.) Honda hybrids cannot accelerate on electric power alone.

Toyota's Hybrid Synergy Drive (HSD) is more complex. The gas engine is unique, utilizing lightweight, low-friction internal components designed to run at a maximum speed of only 5000 rpm. A mechanical compression ratio of 13.0:1 improves efficiency, but the intake valves close so late that the air-fuel mixture experiences only 9.5:1 compression, permitting the engine to run on regular fuel. A unique planetary automatic transmission allows the car to accelerate from rest up to 30-plus mph on electric power only if the driver accelerates gently, which adds significantly to the fuel savings over what Honda's mild hybrid achieves. Toe in deeper, and the gas engine kicks in. Floor it, and the separate generator switches over to work as an additional motor for even more assist. The fuel savings are far less significant at highway speeds, where the engine must run continuously, which explains why the Prius' EPA results are highest for the city test.

Other fuel-saving technologies like continuously variable and six- or seven-speed trans-missions, cylinder deactivation, direct-gasoline injection, variable compression-ratio engines, and even compression-ignition gasoline engines are rolling out or in the works, but few promise to top the hybrid's 25-percent improvement.

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Are Hybrids Real Cars Yet?

The 2004 Prius' styling may be attractive enough to lure persons who don't care about technology or fuel economy for a test drive.

Such folks will discover a roomy, comfortable car that accelerates reasonably well (at 10.2 seconds to 60 mph with the batteries topped up, it's 2.2 seconds quicker than a 2003 Prius tested the same day) and rolls down the road more smoothly and quietly with less steering input required. Larger tires (P185/65R15 versus P175/65R14) endow the new Prius with more sure-footed dynamic handling, though our test car's optional (and aggressive) stability-control system prevented us from quantifying the improvement in our slalom and skidpad tests.

By introducing brake-by-wire technology and further refining the computers managing the various motors, generators, and friction brakes at play during acceleration and braking, the new Prius operates much more smoothly, so the driver is far less aware of the various handoffs occurring between the electric and mechanical hardware. The electric power steering feels more normal, though it doesn't quite match the best hydraulic systems.

Honda's Civic Hybrid is also a far more refined and user-friendly device than the 1881-pound Insight. The two-seater's hard tires and the 4.3-inch difference in front and rear track widths make it a handful to drive on grooved or rutted pavement, and bumps are felt in intimate detail. Thin side glass and minimal sound insulation filter out little or no wind and road noise, and one feels fairly vulnerable sharing the road with jumbo SUVs. While the Insight scooted through our slalom quickest of all (63.1 mph versus 62.5 for the next-best Civic), the control feedback seldom tempts the driver to try heroic handling maneuvers.

The Civic, by contrast, looks and drives like a normal car, tracking straight down most roads with minimal tending. It cushions the bumps better than the Insight can, but falls short of the new Prius' ride quality. With a CVT, the Honda accelerates nearly as smoothly as the Toyota, though it's almost two ticks slower to 60 mph (at 12.1 seconds). Hit the brakes, and the Civic decelerates with that familiar hybrid herky-jerkiness as the battery regeneration comes and goes.

Any discussion of acceleration figures should note the fleeting nature of hybrid power. Climb Pikes Peak, and you'll deplete the battery well below the tree line, continuing on with the tiny gas engine gasping for air. We tested each of these cars with its battery as depleted as we could make it and saw 0-to-60 times plunge by 1.3 and 1.5 seconds for the Hondas and by 3.3 and 4.7 seconds for the Priuses.

Neither Toyota nor Honda requires any periodic maintenance of the battery or hybrid-drive components, and each expects the battery pack to last for more than 100,000 miles.

As for real-world fuel economy, there's still quite a gulf between the EPA numbers and reality (see sidebar). And we still doubt any of these cars is being sold at an old-school by-the-book notion of profitability. In fact, we'd guess the new Prius, starting at $20,510, is the most heavily subsidized car on the market today.

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The Really Long View

Ask auto executives to gaze into their crystal balls and many will say they see the world moving toward a hydrogen economy, with fuel cells as the ultimate endgame. These fuel-cell vehicles will be hybrids, uniting hydrogen and air as a primary means of generating electricity, but relying on some sort of onboard energy storage device as a backup. This battery, capacitor, fly-wheel, or whatever will allow the vehicle to drive away while the cold fuel cell warms up and comes online and will provide instant acceleration on demand (fuel cells can't provide big spikes of power as quickly as drivers have come to expect from their gasoline engines). Of course, it'll also store energy recovered during braking.

It stands to reason that the company with the most experience tuning and integrating gas/electric hybrids may be in the best position to design and develop fuel-cell vehicles that drive like normal cars and trucks once the technology matures and the infrastructure comes online. If that future were five years off, we'd bet the farm on Toyota. It's probably 25 years off at least, but the rest of the industry already has some catching up to do. In the meantime, enjoy the increased performance and economy of your next hybrid car, truck, or 'ute.

What’s Next for Hybrids?

Considering the CAFE pressure on trucks and the inherent profit potential in this segment, it's no surprise that most of the hybrid action in the coming years will be in the truck segment. This fall, Toyota will beef up its HSD system for use in the Lexus RX 400h, followed in early 2005 by the Toyota Highlander Hybrid. The technology is identical to the Prius', but the output of the battery and electric motor will be doubled and a 3.3-liter V-6 will replace the 1.5-liter four. Combined output is said to top 270 horsepower with fuel economy better than the current 27.6-mpg compact-sedan average, which equates to a bladder-busting 600-mile range. All-wheel-drive models will get an additional electric motor powering the rear wheels for improved traction and even quicker acceleration (expect low seven-second times to 60 mph); just don't expect to climb the Rubicon Trail. Toyota may even adapt HSD for use in its forthcoming Tundra-replacement pickup.

This summer, Ford will begin production of an Escape Hybrid, which will team a 2.3-liter four-cylinder engine with a planetary CVT that employs two electric motors much like the Toyota HSD does, except that the all-wheel-drive option will be mechanical, not electric. The hybrid hardware adds 200 pounds, but provides V-6 performance with city fuel economy estimated at 35 to 40 mpg. Trailer towing will be limited to 1000 pounds. Pricing hasn't been set yet, but Ford admits it will be subsidized to some degree.

This fall, Honda will marry its IMA system to a V-6 in the Accord, and the engine will be able to cruise on three cylinders when six aren't needed. The combination is said to provide Civic economy with performance superior to that of the normal Accord V-6.

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GM is currently in production with a mild hybrid system for fleet pickup-truck customers (retail sales begin late this year). It works like Honda's IMA, integrating a 19-horsepower motor into the torque converter of a 4L60E transmission that's bolted to a 5.3-liter V-8. By switching the engine off during idle and deceleration, and by using the motor to smooth torque-converter lockup at low speeds, the system provides a 10-12-percent fuel-economy benefit. But its main attraction to the target audience— building contractors-is its built-in 120-volt 14,000-watt generator. The system will add roughly $2500 to the price of a Chevy Silverado or GMC Sierra.

GM's next mild hybrid project will replace the starter and alternator on the 2006 Saturn Vue and 2007 Chevy Malibu with a nine-horsepower belt-driven electric motor. GM expects to see a 12- to 15-percent fuel savings from this system, combined with a CVT.

Full hybrids arrive in GM's 2007 full-size 'utes and in big pickups a year later. Few technical details have been divulged yet, but we know the system packages within the space of a traditional automatic transmission and includes two planetary gear sets, each of which has a 25-30-horsepower electric motor inside of or connected to its sun gear.

Together, they provide an infinite gear-ratio spread spanning from 4.0:1 to 0.6:1. Working in conjunction with a V-8 that can shut four cylinders down, total fuel savings are estimated at 25 to 35 percent.

At the Detroit Show in January, Mercedes-Benz showed an S-Class concept equipped with a V-6 and a two-motor hybrid-drive system capable of running 50 mph on electric power alone. Total output was a claimed 309 horsepower, sufficient to hit 60 mph in 7.5 seconds and top out at 155 mph, using 20-percent-less fuel than a V-8 S-Class. Mitsubishi also unveiled its Eclipse concept with an E-Boost drivetrain, consisting of a 269-horsepower, 3.8-liter V-6 driving the front wheels and a 201-horse electric motor driving the rear wheels. We suspect this type of "through-the-road" hybrid (the engine and motor are only connected through the road) would be more difficult to tune for seamless operation and may be less likely to see production.