Hello everyone, I am investigating a "device" for saving fuel to see if it works. My guess is no. I want to ask the following... if you take a 2005 Prius, put on a slightly freer-flowing exhaust, and drive it at 65 mph on the cruise control for one hour (65) miles, how many gallons of gas would you expect it to have burned? There were three persons on board, the ride was quite bumpy (over-inflated tires maybe?) and as I alluded to, the exhaust was unnaturally loud. Total fuel consumption I think was 1.06 US gallons (although the driver claimed 0.9 gallons because he spilled some on the ground). I think that comes to 59 mpg. A/C was off, windows up. Temp 55 F, 20% humidity, almost flat course. (Southern California) Now I rented a Gen III Prius myself the next day and drove the exact same course in the exact same way, as close as I could get it. Temp outside was 59 F, and I was alone in the car. I was somewhat surprised to get only 58 mpg. I had over-inflated the tires to 54 psi. Are there any simple things (over-inflated tires, catalytic converter delete, thermostat hacks, etc.) that could be done to a Gen-II Prius to bring its gas mileage to 60-65 mpg at a constant 65 mph? To 70 mpg?