BMW driven more-or-less normally, beats a Pious driven incredibly carefully with an eye on saving gas.
Wonder how all of the Hybrid owners will rationalize this away.
If you drive the Prius watching the instantaneous gas usage, you will get worse gas mileage. The feedback is wrong.
There are tricks to getting the best gas mileage possible (I’ve used them and they work), but frankly the easiest way to get good gas mileage on a Prius is to just set the cruise control and let the car figure out how to maintain your speed.
The Prius driver in this test describes actions that would have lowered his mileage. Some things he doesn’t say make me wonder even more. For example, he says he didn’t use his A/C. The other guy did. But if the other guy needed A/C, it means it was pretty hot. I wonder if the Prius driver cracked open his window instead. That is a bad thing over 40mph on any car — much better to use the A/C.
It also said the Prius guy was having trouble “keeping up”. Since I know the Prius has no trouble driving 80+ mph, I think that means he was allowing it to slow down to try to keep the mileage indicator above 50. That’s a bad way to drive. Better to just get to the speed you really want, and ignore the mileage.
If he wanted to trick the car, the way to do it is to accelerate to about 5mph over what you want, and then drift down to below your speed, and then accelerate again.
Here’s the reason: The Prius in the end is just a gasoline-powered car, and won’t get the gas mileage of a diesel. But what the Priuse allows is to operate your gas engine in it’s most efficient level. That’s however at a power range above what you need to cruise.
So if you try to maximize your instantaneous fuel mileage by maintaining a strict cruise speed, you will operate the gas engine in a slightly lower overall efficienty range. If instead you ask for a little MORE power, it can take that extra power and drop it into the battery, and then later use it out of the battery and cut off the engine.
Here’s the rub though — If you try to keep moving above 60 mph or so, you can NEVER do that with JUST the electric motor — so the engine will still be running, and will be running at a lower efficiency if you are also using the battery.
That’s why it is more efficient to accelerate/decelerate (not a driving style I use or like). The deceleration allows the engine to cut off, and the acceleration happens with a higher efficiency part of the engine performance curve.
But seriously, above 55mph the Prius is only “fuel efficient” because it has a small motor and a really good coefficient of drag. The battery is (as I explained above) almost useless (unless you have a lot of uphill/downhill parts to your trip), you don’t hardly ever brake, and you are never sitting around not moving.
If you push the car over 75 mph the small motor is overtaxed and drops to a lower performance curve (in this case a larger engine might be still in its highest part of the performance curve). And if you opened the windows you destroyed your low coefficient of drag.
BTW, the Prius could be more efficient by nature, but it gives up some efficiency to operate in regions which generate less pollution. I imagine the BMW didn’t have that limitation.