2010 Toyota Prius Review – Driving Impressions

By IBxAnders - January 6, 2010

For 2010, the new four-cylinder engine goes from 1.5 to 1.8 liters,
and horsepower increases from 76 to 98. Combined with the electric
motors, there’s a total of 134. The larger engine provides more torque,
allowing the Prius to maintain freeway speeds at lower rpm, boosting
fuel mileage. It’s an Atkinson Cycle engine (different valve timing and
breathing). CO2 emissions have been reduced from a score that already
tops the charts.

The Hybrid Synergy Drive system, with two compact motor generators
within the transaxle, increases operating voltage from 500V to 650V.
Gear drive replaces chains in the motor, increasing the motor’s rpm to
13,500 from 6400. The improved Power Control Unit (inverter) is more
compact and cooler running. The Nickel-Metal Hydride battery pack is
more compact and powerful, like all the rest. All told, there’s a
savings of 65 pounds.

The accessory drive belts have been eliminated, with such things as the
AC compressor and water pump now driven electrically. This means the
air conditioner works, though not full blast, even with the engine
turned off.

There are three driving modes: EV, or all-electric, with a very limited
distance at 25 mph or less (if there’s enough juice in the battery),
most useful for underground parking garages (or maybe your teenage son
taking his girlfriend home late); ECO, which minimizes fuel consumption
by reducing the throttle opening and restricting the air conditioning;
and Power for full acceleration.

The difference between Power and ECO is 4.1 seconds from 50 to 70 mph,
versus 5.8 seconds. If you’re in ECO and floor it, it will kick itself
into Power, which is also the default mode when you start it up. So you
have to set ECO mode at every stop, to get the best mileage. But we
wonder why anyone would drive around town in Power mode, because ECO
feels no slower. The Prius accelerates from 0 to 60 mph in 9.8 seconds,
usually fast enough though slow by modern standards.

When you accelerate hard and it kicks into Power mode, it can be
abrupt, like a transmission kick-down. But like all hybrids it uses a
CVT, continuously variable transmission, which is technically not an
automatic because it doesn’t have gears. Most of the time you’re not
aware the Prius CVT is there, which is how they’re supposed to work.

The Prius is EPA-rated at 51 city and 48 highway, for a combined 50
miles per gallon. We got 54 mpg driving gently but still sometimes
using Power mode, over 23 miles of city-highway driving; and later 70.5
mpg over a 34-mile street course in a competition with other automotive
journalists. We averaged 28 mph, about average for the group.

The winner, a specialist hypermiler, got 94.6 mpg driving by all the
tricks. He averaged 19 mph, moving at about 30 mph in the far right
emergency lane of the 50-mph highway, showing that it takes travel in
an unreal world to achieve those big numbers. An opposite leadfoot
extremist managed to get 26.8 mpg. The other 26 of 28 drivers got
between 63.3 and 75.3 mpg.

A flaw in the new Prius is its bumpy ride: pretty rough over patchy
stuff, we noted during our test drive. There’s a new suspension with a
slightly wider track and increased roll rigidity. Earlier we rode for
more than an hour in the back seat of an ’08 Prius (the
previous-generation model) and it didn’t feel as harsh. The standard
15-inch wheels are fitted with low-rolling-resistance tires
(195/65R15), and maybe that explains it. We also drove a Prius with the
optional 17-inch wheels and 215/45R17 tires, which felt slightly
smoother although theoretically they should be firmer; we got better
mileage with them, 57.4 mpg, although the Prius chief engineer said the
17s deliver about 5-percent less mileage.

We and other autojournos thought the road noise seemed high, despite
Toyota’s claim that the new Prius is quieter, and maybe both things are
true. Press materials say there’s more sound insulation, though the
insulation weighs 7.7 pounds less, a benefit of new materials designed
to absorb sound instead of insulate against it.

The four-wheel disc brakes (replacing rear drums) are sensitive, and we
could hear rubbing at low speeds with ours, partly because there was no
engine noise when backing off, and possibly because of the regenerative
braking component: the more you use the brakes, the more battery juice
you build up, enabling you to use EV mode more. On our 70.5-mpg run, we
gently used the brakes a lot in city traffic, so we would get as many
blocks as possible out of EV mode.

The handling is nimble around town, although it turns heavy and slow,
though not imprecise, if you try to drive it aggressively in corners,
something not too many Prius owners do (an understatement). However its
cornering is much improved with a new chassis and suspension. The
slower you drive it, the better it is. The new Prius has gained 110
pounds overall, mostly from its stiffer body structure, despite the
65-pound loss in the hybrid componentry.

We tested the optional Intelligent Parking Assist, part of the Advanced
Technology Package available for Prius V, which parallel parks the car
for you, if the space is big enough. It needs a margin of 7 feet 9
inches, more than half the length of the car; most drivers can handle a
space that big with no worries, so it’s fair to ask what’s the point,
unless you’re a total spaz at parallel parking. Like many high-tech
innovations, it does it because it can.

You can set the distance you desire to the curb. Pull up, line up,
press the button, it tells you when to go; then release the brake pedal
and take your hands off the steering wheel and let it do its thing.

2010 Toyota Prius Review – Driving Impressions

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