Efficiency and traction

1. Driving and Efficiency:

Assuming you won't have to immediately stop, moderately aggressive acceleration is more efficient than granny driving. All of the energy comes from burning gasoline in the engine, so the most efficient way to use a Prius is to burn gasoline efficiently and immediately use that energy to move the car. This means you want to accelerate in such a way that the gas engine runs at its most efficient speed and load, without drawing power from the battery or storing excess energy back into the battery.

2. Driving in rain and snow:

Obviously tires are the main contributer to traction. They are the only part of the car to touch the road, so *all* traction comes from the tires. Traction control and driving technique can help get the most from your tires, but they can't produce traction when it isn't there. In other words, traction from your tires is the limiting case. You can make the traction worse by driving poorly, but you can't make it better than the limit set by your tires.

As for traction control in the 2004-2005 Prius, some Prius seem better than others. It appears that there is some individual differences from car to car. That said, even the best 2004-2005 Prius have touchy traction control. It was improved for 2006 and improved again for 2010.

Tom

 

The ICE, when running, should be kept in some throttle limits, to be working in the best BSFC region. Prius does that for you, as long as not floored.
It is very simple.

If you slowly pull, without ICE, it is also very efficient (comes from batteries). The difference is subtle, that energy will come of the ICE (at the end), but, most of the times, comes from braking, which is unavoidable.

 

Electric motors are efficient, but (as you point out) the energy originally had to come from the engine. Because of those energy conversions (chemical -> thermal -> electrical) the overall system efficiency is much less. It really does increase fuel economy to use the battery as *little* as possible. In a Prius that means, don't creep away from a stop on battery alone.

 

I agree with what people are saying, but just to clarify - accelerating only has to be strong enough to avoid going on all battery power, doesn't have to be extra aggressive. Over-reving the engine isn't good for mileage either, plus it brings in the battery - on the energy diagram on the MFD, try to use ICE only, without battery, and you'll be fine.

Traction does vary on the early Gen II Prii, but tires definitely help. It seems on some cars, if it detected any slip at all, it would shut down the axle entirely. So with better tires, you're less likely to get any slip in the first place. This was mostly seen on snow and ice, not rain, but some people reported it in certain muddy conditions or uphill on loose gravel. I've never had a problem with my 2006, some people did report problems on the 2006 yet, but the most reliable TC problem reports were on the earlier cars.