[M_a_t_t]

Originally Posted by Yippeekyaa

Wow, how nice of you to ask others for specific testing ideas and then tell them to go test it themselves(note sarcasm). Throttle stop testing doesn't work on vehicles with drive by wire and a cvt transmission which makes that method of testing useless on the most plentiful hybrid sold in the world.

To find the change in drag that the template add-on would make using the pressure change would require him to

Originally Posted by Road Vehicle Aerodynamics, AJ Scibor-Rylski, pg 15

Integration of the pressure around the circumference (he is referring to a cylindrical example for calculating drag based on pressures)will produce an aerodynamic force which in this case would be simply the drag of the cylinder.

My summary: 1. Plot the pressure over the entire car. Then 2. integrate that data to see the change in drag. Then repeat those 2 steps with the modified version.

So it would be infinitely easier to just do throttle stop testing, which is probably why he suggested it.

It doesn't look like either of them have a prius so I'm not sure why you projected that onto their interaction. You are correct though and can only suggest you try something similar to Vmans test (I bolded the part I was referring to).

Originally Posted by Vman455

-I did test the air curtain ducts, both with coast downs and fuel economy over a section of road. The first version of the front ducts increased drag about a third as much as rolling all the windows down, but adding the rear ducts to it reduced drag so that there was no change from no ducts at all. The front ducts also noticeably and negatively impacted stability--the front end felt "squirrelly" in crosswinds, passing truck wakes, etc.

Coast down tests with the front ducts on and off (with rear ducts on for both) were inconclusive--there was just too much variability to measure a small effect. So I went out on a calm night on US 45 and measured fuel economy over a 3-mile section north and south, 6 runs in each configuration. Front ducts alone showed 0.29% decrease in fuel economy at 55 mph (70.1 mpg average base/69.9 mpg front ducts), but adding the rear ducts showed 1.28% improvement in fuel economy over no ducts at all (70.1 mpg base/71.0 mpg front and rear ducts); it appears the efficiency improvement is attributable to the rear ducts or some synergistic effect between rear and front. Further, the car is extremely stable with the new front ducts, which is reason enough to keep them on.

I don't have a prius either so I don't have any first hand suggestions.