Review of 2007 Toyota Prius
The Prius is a really some kind of futuristic flying saucer cunningly
disguised to look like a car. Warp this baby back to 1980 and the natives
wouldn't be able to fix it. Heck, you can't even push it if the
batteries die. For instance:
Why Prius ?We were looking for something with significantly better fuel economy and lower emissions than a regular car. In the current Canadian market, that means a hybrid. There seem to be no viable battery/electric or fuel cell cars available at this time.
Many car manufacturers are still advertising how powerful their cars are, or how fast, or how well they perform on winding highways with no other cars in sight. As if most drivers ever see roads like that (OK, the Duffy Lake road is pretty neat).
The Prius, on the other hand, is great for real life - being stuck in traffic.
The gasoline engine cuts out, and it will creep forward quietly on
battery power with zero emissions. Or, with the EV button (standard in Europe,
for North America see here
or google "Prius EV mod"), you can maybe make it to the corner store on battery alone.
How does it work ?Pretty well, considering. (no, really). The official website is www.toyota.ca (Canada) or www.toyota.com (USA), but it's hard to find much technical information. The best publicly available description may be in the Emergency Response Manual and Dismantling Manual. Full manuals may be bought or viewed online for a fee (a few Euros) at techdoc.toyota-europe.com or www.techinfo.toyota.com (US only)
See this page (Graham Davies) for an explanation of the drive system.
Essentially, the Prius has a gasoline engine and two electric motor-generators connected to a planetary gear system which drives the front wheels. Electric power is provided from a 200V NiMh battery via a fluid-cooled inverter. The motor-generators provide regenerative braking, 100% of the power in reverse, and extra power for acceleration. The Prius doesn't actually have any gears in the normal sense; the gasoline engine normally runs at a fuel-efficient low-emission rpm and one of the motor-generators adjusts the torque on the other end of the planetary gear to give the desired road speed. Think of a normal car with the left driving wheel spinning on ice and the right one stationary - by braking the left wheel you could transfer some torque to the right one to move forward. (Later) - I realize now that the preceding sentence is rubbish, at least the bit about always running at an efficient RPM. From the RPM-speed graph further down, it is clear the engine RPM is all over the place. It does spend a fair bit of time at about 1300 RPM, though, which is probably the battery-charging regime.
It is not possible - at least, in the factory-standard model - to charge the NiMH battery in any other way, so you are still dependant on gasoline, though Hymotion makes a conversion kit.
A small 12V lead-acid battery provides power to run the computers, lights, and control systems. It is recharged from the HV system via a DC-DC converter. As far as I can determine, it cannot be used to start the car; the motor-generator is needed for that, powered by the high-voltage battery. But if it runs flat the door locks won't work. (Since the 12V battery is in the back, which won't open without power, you have to connect jump cables to the fuse box next to the engine)
PerformancePretty good, IMO. OK, it's not going to win drag races or tow a 2000kg boat, but it did OK on our trip across the mountains, taking the grades without gasping for breath and overtaking most everything on the road (100kph limit, and 30k over risks a ticket for dangerous driving, so it's no autobahn...). The stock tires are a bit iffy on ice, though.
Easter EggHolding the "Info" button down on the centre console while turning the lights on and off brings up a diagnostic display.
Road TripAbout 1720 km through the Rockies from Vancouver to Prince George and back, plotting energy consumption against elevation: PG.html
Fuel ConsumptionThe book says something like 4.7 l/100km. We get about 5.0 in the city, maybe 4.7 on the highway. The tank is smaller than average, and I think we get about 500km/tank. For comparison, our Toyota Previa (4cyl AWD minivan) gets about 13 l/100km, and my 200cc motorcycle 2.8.
Gripesstuff I'd change if I could
August 2008. Drove (4 passengers, luggage, frame tent, stove, cooler etc.)
from Vancouver to La Jolla (near the Mexican border)
via Las Vegas, San Francisco, Death Valley, Anaheim (not necessarily in that order).
Sept. 2008. Bought a hitch kit to support a bicycle carrier. There's lots of these now; they all look much the same and bolt on to body in place of the tie-down brackets. You have to cut the plastic underbody cover somewhat.