[Ptero]

The drag coefficient on the Scion sucks eggs. I've seen it rated as high as .37 while the Prius is rated at .26. That is an astounding difference!

At speeds above 60 mph, more than half an average vehicle's horsepower is used simply to push air out of the way. If you are so inclined, you could find out how fast your Scion would go to create the same amount of drag that the Prius encountered at 65 mph. The disappointing result will likely be in the mid to high 40s.

Use this formula.

The force of drag equals half of 1.3 kilograms per cubic meter times the speed times the frontal area of the car times the coefficient of friction.

Sad to say, you can try all the aero mods on Ecomodder but you will find the single most effective thing you can do to try to close in on the mpg of the Prius is, by far, to slow down to that 40 mph range in top gear and keep your speed constant on level terrain.

As to the onboard electrolysis unit, I have yet to see one single study that indicates there is any measurable gain. Fundamentally, pulling energy from a closed system (your car) to manufacture a secondary form of energy (hydrogen) that is returned to the closed system (your car) can result only in losses associated with the unnecessary conversion of one form of energy (electricity) to another (hydrogen) which is simply returned to the system.

In fact, if you have a vehicle with an onboard electrolysis unit installed, you should be able to achieve a slight performance gain by removing it.

Now, if you were to take hydrogen from outside the system and add it to the system, that would certainly be beneficial. But that's not what we're talking about with onboard electrolysis units.