Hi All: This time, the 2025 Toyota Prius Prime in XSE Premium trim with an EPA rating of 50/47/48 mpgUS city/highway/combined. 2025 Toyota Prius PHEV aFCD Calibration Drive(s) I refueled with an initial top off in Hawthorne, CA as posted in the "What's your current fuel prices?" forum thread(s). The notoriously tough to top off, 5th gen Prius PHEV being refueled for the first time under my watch. I completed the 2025 Toyota Prius PHEV's odometer study and aFCD calibration with a refuel in Tustin, CA. That dent above the passenger right front fender body panel was there when it arrived. Odometer Study 109.4 miles actual vs 106.2 miles actual. This is a rather large 3.0% positive odometer offset. And the aFCD study concludes with an unusual positive offset mostly due to the odometer offset. The 5th gen Prius and Prius PHEV is tough as you can never be sure a top off has occurred without a top off, drive for a block with a few hard braking scenarios and top off again. In any case, I did the best I could at the two Costco top offs. 330.5 miles at 64.6 mpg indicated - 340.4 miles actual on 5.147 gallons top off to top off = 66.1 mpg actual vs 64.6 mpg indicated or a positive 2.3% offset. I am a little concerned with the large 2.3% aFCD positive offset due mostly to the XLEs 19's providing a 3.0% positive mileage offset. Given the 5th gen Prius' tough top offs, maybe I was shorting the fuel but regardless, the results are the results for the upcoming Speed vs FE data I will collect possibly tonight after midnight. With the aFCD calibration complete, next up, the Steady States. 2025 Toyota Prius Prime XSE Last night just prior... Temps of 64 to 65 degrees F with calm winds. The speedometer offset indicated none: 50 mph indicated = 50 mph actual 55 mph indicated = 55 mph actual 60 mph indicated = 60 mph actual 65 mph indicated = 65 mph actual 70 mph indicated = 70 mph actual With an EPA highway Crossover (47 mpgUS), straight line analysis indicates a great 73.4 mph. The Prius PHEV with the 19" Michelins a Cd of 0.27 taxed did not harm the powerful 2.0L much but just imagine if we could pick one up with all the options we want but equipped with nice looking 15s, 16s, or 17" alloys for much higher efficiency? Wayne
Pretty amazing that it's able to achieve almost 75 mpg steady state at 50 mph, despite the (relatively) heavy curb weight, 2L ICE and "huge" 19" wheels. I'm assuming it's still running on pure ICE at this steady state, no (net) battery draw?
That's how Wayne sets up the test, by running down the battery beforehand. add: In steady state, the wheel size does not matter. The normal/narrow width of the 195/50R19 tires have the same frontal view as prior Prius, just taller but aerodynamically hidden bulk. add2: 2023 Prius LE - Wayne's results showed 79.5 mpg at 50 mph, so yes, excellent result for the Prime XSE.
