A real, frugal city car-not a green-geek novelty.
by Bengt Halvorson
I probably have more "green" friends than most automotive writers, and my planet-conscious pals constantly pose questions about "those new hybrids" as if they're the next big thing since frozen yogurt or TofuRella - cars that you can use without the guilt of contributing to global warming and the depletion of fossil-fuel resources, cars that set a trend for others to follow.
Until recently, my only experience with the $19,995 Prius was when Toyota brought a few Japanese-market cars to the U.S. more than a year in advance of its U.S. introduction. Although Honda's Insight (which went on sale in the U.S. before the Prius) was still in the development stages at that time, the Prius had already been on sale in Japan for nearly two years (it made its debut there in 1997). In a short drive then of a right-hand-drive Prius, my colleagues and I were impressed with the seamlessness of the hybrid drivetrain but critical of the car's lack of power at higher speeds.
Since then, Toyota has tweaked the Prius for the American market with a slightly more powerful engine, new battery packs, and revised hybrid system behavior. Naturally, I considered it my duty to you and to my tree-hugging buds alike to revisit this benchmark. Mainly, I was interested in two main things: is the Prius a car that I could live with as well as any other small car from day to day, and does this tech powerhouse actually return the lofty gas-mileage figures that it promises (52 city and 45 highway, according to the EPA)?
I found my answers - both yes and no.
Good news for granolas
The good news for Toyota and for granolas everywhere is that driving the Prius is not the work-in-progress, techno-geek experience you might think. In fact, most of the time the hybrid system does its job so unobtrusively that you don't even know what's going on, unless you're looking at the special feature screen on the onboard computer that shows you, with arrow diagrams, whether the electric motor, gas engine, or both are providing power, and when the battery packs are regenerating. The column shifter and center-mounted LED gauge cluster are a bit different from other small cars, but otherwise you just shift into Drive and go. The Prius feels and drives much like a normal small car.
How does it work? The Prius has a true hybrid system. It can run independently on either electric or gas power as needed, and it doesn't rely on the combination of both at all times. A planetary gear setup manages the flow of power from and between the engine, motor, and generator. The motor operates from a standing start and whenever very little power is needed to keep the car moving. Once the gasoline engine starts up, the continuously variable automatic transmission brings the revs in the most efficient range. A regenerative braking system captures some of the torque used in braking and converts it back to electricity to help recharge the batteries. The rest of the batteries' recharging is handled through normal engine power. The gasoline engine, with VVT-i variable valve timing, a high 13:1 max compression ratio, and a design that emphasizes efficiency over everything else, makes its peak 70 horsepower at its redline of a leisurely 4500 rpm (up from 4000 in earlier versions), with peak torque of 82 lb-ft at 4200 rpm. On the other hand, the electric motor makes 44 horsepower from 1040 to 5600 rpm and a surprising 258 lb-ft of torque available at 0 rpm (not a misprint: electric motors are just that way). With near-opposite power curves, the two power mills seem ideal partners in a hybrid.
All of the elements of the so-called Toyota Hybrid System are computer-controlled and monitored to make the transition between power sources as seamless and efficient as possible. In most situations, the gasoline engine will shut itself off in drive at a stoplight. Lifting off the brake, the car will 'creep' forward just as a gas-powered car and have plenty of power from a start. While accelerating, usually between 5 and 20 mph, the gas engine will silently start, build revs, and join the electric motor in propelling the car forward. At just about any speed, if you coast for more than a few seconds the gas engine will automatically shut off to save gas and cut emissions. You really can't feel most of these power changeovers, except for when the gas engine shuts off at stoplights-which is a disconcerting feeling at first.
City natural, highway novice
The hybrid system actually gives the Prius enough oomph at full throttle to rip the front tires loose from a stoplight-a ridiculous image, but an image nonetheless that proves the Prius is no slug in city driving. Even under full throttle, the hybrid system keeps its composure as the electric motor helps the gasoline engine get the car quickly underway.
If we could wish for one thing about Prius to be changed, it would be the twitchy, overboosted steering. At low speeds, the quick ratio and high power-steering boost is nice for parking and maneuvering between lanes, but at higher speeds it leads to an unsettled feeling, it tends to wander, and it needs frequent little adjustments. The Prius also tends to tramline severely on the snow-chain rutted highways of the Northwest, and the slab-sided car feels quite susceptible to sidewinds.
More problematic is its open-road behavior. While the Prius feels like a natural in town, the hybrid drivetrain also feels remarkably out of its element in high-speed highway driving. The gasoline engine occasionally buzzes coarsely, revving up and down with the slightest inclines, with the transmission sometimes indecisive for no apparent reason. Keeping a steady speed is difficult. Mix that with the wandering, twitchy steering and you have a difficult long-distance driver.
The brakes have a unique, drive-by-wire setup in which regenerative braking handles light braking applications, followed by good ol' front discs and rear drums for the real stopping power. The process makes them hitch up in a non-progressive, but predictable way that's reminiscent of power brakes from twenty years ago. Press the pedal just a little and you can feel the regenerative braking. Press a little more, and not much happens. Then you get to a level where the boost kicks in and the brakes grip with more stopping power than you want. After a few stops we got used to it.
Aside from the hybrid powertrain and less-than certain handling attributes, the Prius really feels like an ordinary small car, with a reasonably large trunk and decent space in the back seat, at least for shorter trips. It really is remarkably roomy, considering its diminutive exterior. The front seats are typical economy-car issue, with very little support and no adjustment for cushion height or tilt.
Toyota otherwise has done an elegant job with the inside. The silver-toned buttons, though slightly out of place, add a nice touch. I didn't, however, get used to the center-mounted LED gauge cluster and the touch screen. The combination of both seemed a bit distracting at times at night.
That touch screen has several useful features, though. A consumption mode follows instantaneous fuel consumption with a bar graph, and then a graph plots five-minute average fuel economy figures for the last thirty minutes, indicating major power-regeneration points. An energy mode shows, with blinking arrows, the direction of power between components of the hybrid drivetrain. You can follow in real time when the power is coming from the engine, motor, or both, when braking regeneration is charging the batteries, or when engine power is charging the batteries. A display on the interface, much like that of a laptop computer, shows approximately how full the battery is. I never saw it fall below half full.
Prius rides on a wheelbase that's stretched about seven inches longer than the Echo, but otherwise the two cars have similar dimensions. Despite the two cars' obvious similarities, including similar styling and the same weird, gauges-in-the-middle layout, Toyota says that the cars have little in common and aren't even on the same platform. At 2765 pounds, Prius is more than 700 pounds heavier than a four-door Echo, which in five-speed manual form is rated at 34 city, 41 highway.
The all-electric heating and air-conditioning system is instantaneous and more than adequate. There's no wait for the engine to heat up in the winter before heat is available. It gets hot fast, so the automatic setting is useful for comfort.
What about fuel economy?
Now for the part you've been waiting for: does Prius live up to its fuel economy claims? I did pay extra attention to the fuel consumption. Each fuel fill was made with the same pump, carefully trickling the fuel in to the same point in the filler neck, because when you have a vehicle that uses as little fuel as the Prius, every little bit counts. To validate-or at least back up-my results, I let the onboard computer compute my mileage as well, and it was always within one mpg of my pump-and-odometer calculated results.
To figure out how to get the best mileage, I divided my time behind the wheel into three different driving styles. First was nearly 120 miles of daily errands and commuting, driving with the flow of traffic and pretending that I was behind the wheel of a normal car. I averaged a frugal 48 miles per gallon.
Next, a 36-mile, "fuel economy" loop, made up of about two miles of dense stop-and-go city driving (averaging no more than 10 mph), 10 miles of suburban stoplight-every half-mile driving in which I averaged 30-40 mph, and then 24 miles of highway driving, ranging from 50 to 65 mph. During this loop, I was gentle on the throttle and drove as I would a gas engine for best fuel economy. My efforts were rewarded with a good, but meager, 44 mpg.
Finally, I decided to test my ideas that had formed about what factors into Prius's consumption. I topped off the tank carefully again, and over the next 40 miles of urban and suburban driving I drove the Prius in a spirited manner from stoplights, not paying special attention to how easy I was on the throttle. This driving method returned 47 miles per gallon.
Toyota's Ming-Jou Chen confirms that the driving pattern for getting the best mileage from the Prius is quite different than for an ordinary car, and that fuel consumption depends on the use of accessories like the climate control, which cause the gas engine to start more often to keep the battery charged. Unusually cold or hot weather will cause the Prius to get worse mileage. Conditions during my drive were mild, in the 50s. I still think, after my time with the car, that the EPA's figure of 52 city is maybe a bit optimistic.
A gridlocked green's dream
After all of this playing this mad fuel-economy game, the Prius' strengths and weaknesses had become more apparent. In the city, the electric motor can provide the short bursts of energy needed, while on the highway the electric motor can't keep it up and it just isn't efficient anyway. What backfires for the Pruis on the highway is its sheer mass (for such a small car), which the poor little gas engine just isn't up for the task of hauling. It does the job alright, but feels strained on the highway where it has more of the responsibility.
The fuel-economy graph confirms that it isn't exactly operating in its efficient zone at Interstate speeds. On a straight, level stretch of highway, the touch-screen computer's instantaneous fuel economy bar graph indicated nearly 50 mpg at 60 mph, but bringing the speed up to 70 mpg dropped the gas mileage into what appeared to be the low-to-mid thirties, and a steady 75 corresponded with not much more than 25 mpg. In short, the Prius gets great mileage if you can control that heavy throttle foot at highway speeds, if you do mostly low-speed urban commuting, or if you live in one of the New England states (or Hawaii) where the speed limit is still 55. In town, you can hot-dog it as much as you want and you won't be penalized much, but on the highway the Prius can suck more gas than you'd think.
If it's more highway driving you do, you might be happier with Honda's Civic HX, which gets an honest 40-something miles per gallon in real-world highway driving (EPA rated 36 city, 44 highway), and is available with either a five-speed manual or a CVT automatic. If you have your mind set on a hybrid, also check out the Honda Insight, which is, unfortunately, only a two-seater that looks and feels less like a normal car. The Insight gets a higher 61 city, 68 highway rating from the EPA, but the Prius beats it for emissions with a California SULEV rating. (Look for a full road-test review of the Insight in TCC in a few weeks.)
There's no doubt that Toyota invested a tremendous amount of money to bring the Prius to production. Toyota won't reveal exactly how much it has spent on its hybrid projects, what else is in the works (a hybrid HV-M4 minivan concept, rumored to be on the way to production, was shown at the '99 Tokyo show), or how much it is losing per vehicle (the base price is only $19,995). Prius has been much more of a sales success than anticipated: 6860 have been sold so far, and another 1200 orders are queued up.
The Prius is an excellent engineering showcase and hopefully a predecessor to a whole fleet of hybrid-drivetrain vehicles. Kudos to Toyota for getting it out to consumers, and for showing the car-buying public that hybrid drivetrains can be practical and reliable.
© 2001 The Car Connection