#DAS09 We've given you the full low-down on the 2010 Prius. We've mentioned its stunning sub-10-second 0-60 mph times. We've written about its 50-mpg average EPA fuel economy.
But here are two pieces of Prius truthiness:
The 2010 model is the most aerodynamically slippery production car in the world with a drag coefficient of 0.25.
And the name Prius is Latin for "before" or "formerly." Toyota was probably thinking about the former and not the latter when it came up with the name. And here we always assumed that the name was just one of those made-up names like Achieva, Altima and Aveo.
Maybe by the time Toyota introduces the fourth generation Prius we'll have figured out why the company's three-oval badge looks like it does. -- Daniel Pund, Senior Editor, Detroit
actualsize says:
11:48 AM, 01/12/09
What? You don't like the Toyota sombrero?
And Toyota's use of the coefficient of drag (Cd) to bolster a claim of being the most aerodynamically slippery production car is an example of half-truthiness, even if the 0.25 part is fully truthy.
Cd by itself is just about worthless. You need to multiply the Cd by the frontal area to get a car's drag -- the bottom-line measure of aerodynamic "slippery-ness."
1487 says:
12:13 PM, 01/12/09
not only that but cD has little meaning at city speeds where the prius does its best work. Cd is important if you are talking about trying to hit 150mph or more. It really has little impact on fuel economy as legal speeds.
carlisimo says:
01:19 PM, 01/12/09
Cd is important at 50mph and up, imo. Certainly at typical freeway speeds. If the Prius's weakness is those speeds, well, they've done something about it.
1487 says:
01:24 PM, 01/12/09
the new engine is what Toyota credits with increasing highway mileage. Cd is not that important, especially when most cars are close in that regard. It would be different if you compared the Prius to a bus or something. Notice Toyota doesnt mention any actual benefits to that low cd.
firstwagon says:
03:02 PM, 01/12/09
Cd ( or total drag as actualsize points out) is important at all speeds, it just gets exponentially more important the faster you go.
Even at legal speeds it affects your mileage far more then you think.... especially on a low power engine like the Prius has.
billt9 says:
04:38 PM, 01/12/09
The Cd stat is worthless.
Smart people just look at the highway mpg, the actual end result.
drwales says:
05:42 PM, 01/12/09
Well, drag goes as velocity squared, so it's not exponential, but it does get more important the faster you go.
It is important, but only the truly geeky will ooh and aah over it, as opposed to the masses who will drool over 50+ mpg
firstwagon says:
08:15 PM, 01/12/09
How is velocity squared not exponential?
V is the base and 2 (squared) is the exponent.
Smart people will look at why it gets good mileage on the hwy. The simple masses will just look at some numbers a government agency put together.
billt9 says:
08:37 PM, 01/12/09
"Smart people will look at why it gets good mileage on the hwy"
...at this point i would cite cars that have awesome Cd but get crap fuel economy. Unfortunately that is too much work to look up right now and I will defer that task and say
low Cd != good mpg.
Some cars manage to have such terrible drivetrain loss that makes looking at the Cd not useful.
Cd is but one component of the net sum, Cd does not correlate linearly with the final result.
lawmonkey says:
06:41 AM, 01/13/09
Funny comment about the emblem - it has always been something that I was curious about. My best guess (obtained by being stared at by the emblem on steering wheel for 100K+ miles) is that if you stare at it, you can actually spell out T-O-Y-O-T-A with all of those ovals, kind of like how a digital clock can make the numbers 0-9 out of an 8. (PS - try not to stare at the wheel while driving - trust me on this one).
smbrm says:
11:40 AM, 01/13/09
I always thought the emblem was a stylizes T inside a flattened globe!
I wonder when we will hear about the coupe version. Probably close to when the Honda CRZ gets launched?
firstwagon says:
03:23 PM, 01/13/09
"...at this point i would cite cars that have awesome Cd but get crap fuel economy"
And they would get worse mileage if they had a bad Cd.
Drag of a car has nothing to do with drivetrain issues. Lower drag equals better hwy mileage on all cars regardless of other factors.
How low it goes depends on a lot of issues but the less drag, the energy needed to propel it down the road and thus less gas burned.