Just changed the oil and filter on my 2025 XLE with the odometer at 600 miles. I then drove from Orange County in SoCal to San Raphael in the Bay Area, a distance of about 450 miles. My route took me along the 405, 5 and 580 freeways. The 5 fwy has some pretty good climbs before dropping down into the CA central valley, and similarly the 580 has some good elevation approaching the Bay Area. I set my ACC to 80 mph (pretty much what traffic was doing in the fast lane). I had a hitch mounted bike rack with a mountain bike loaded up on it, which seriously effs with the aerodynamics of the car. The car returned 35 mpg for the trip!! Should I be concerned? Thoughts....
Like many cars, it's MPG is directly impacted by the MPH and the terrain. I made the same trip this weekend in a 2024 XSE Prime. I drove at the escalated speed of 75 to 85 MPH. I normally make it from the gas station at the base of the grapevine to the Altamont Pass without running low on gas or electricity. I pulled into the corner gas station with only a few miles of gasoline range left. The traction battery still had 20% of it's remaining capacity as we pulled into the driveway. In general, if you want good mileage, don't drive into a headwind. Use the cruise control to moderate your use of gas.
IMHO; that's kinda expected doing 80 mph with the additional wind drag of the bike on a rack. That bike back there acted like a drag parachute. Arriving with 20% traction battery remaining means that you weren't coasting much or using the battery much - that was pretty much all 2.0L motor dragging that huge heavy car. Was the car in ECO mode? I'd wager the mpg will move up to it's normal average on your normal commute.
I don't really calculate the MPGs any more. It's It varies from somewhere in the 40s to somewhere in the 50s, depending on the use of the energy that I stored from the grid. A trip that stays in EV mode uses no gas at all. A trip that is 100% gentle down hill grade at 55 MPH uses very little gas. There is a display that shows the MPG on the screen, but I know that it's a mixture of the EV and gas modes.
I'm not sure that it's all that huge nor heavy. From the net: 3,571 lbs for the XSE Premium Prime. The 2015 Prius weighed in at 3,072 pounds, so that's a 500 lb difference to provide a much, much, snappier response. Since that's the same weight as a 2024 Camry hybrid, the "huge and heavy" are pretty much not applicable. It's not like it's a 4,398 lbs Tesla Model Y.
Yeah 80 MPH with bike rack on the outside is not the Prius sweet spot. I'd not use this scenario to judge being concerned or not. On mine, I've seen low 40s on long highway drives 75MPH+, etc. I'd say sweet spot is 55-65MPH. Anything over 65 and your MPG will suffer.
Between my old Prius C and my current; I was still a field service tech doing 50K+ miles annually - the mpg began tapering off above 68 mph. It begins dropping off a cliff beyond 72 mph.That was over various terrains and mostly highway miles. You hang a bike back there; it might as well be a sail. You can probably make-up some of it if you drafted behind a larger car - easy to do in a Prius C; but catching and keeping up with them is the challenging part. YMMV
Completed the return trip yesterday. This time, just to see what effect the bike hanging off the back had, I put the bike in the car, and folded up the rack (1-Up rack). Kept the same speed - ACC set 80 mph - and the car returned 43 mpg, an 8 mpg improvement. As some mentioned above, the bike/ rack combo hanging of the back does some serious damage to your mpgs. Can anyone tell me what safety feature to turn off when backing up with the bike/rack hanging off the back? The car protested loudly and would continue to slam on the brakes as I inched backwards. Quite embarrassing leaving a crowded trailhead parking lot.
PKSB. You access it through the settings menu on the main gauge cluster using the steering wheel buttons. Go to the gear icon and keep going right. It's on the second page of options. The icon is a car and a traffic cone with a little impact symbol between and above. I'm not sure if turning it off is persistent, or if you have to shut it off every time you start the car.
So, I did the same trip up to the Bay Area as in the first post of this thread - 430 miles and speeds between 70-80 mph on the long fwy sections. No bike hanging off the back of the car this time. I got 44 mpg on the trip up. While in NorCal I stumbled on this article (2025 Toyota Prius Owner Defies Manual With 91 Octane: Real-World 61.1 MPG Test Beats Regular Gas Efficiency) regarding the use of premium fuel, and the noticable improvement in mpgs. So, I decided to see if it would make a difference to my 2025 XLE on the return trip to SoCal. I had a little over half a tank of regular 87 octane fuel when I filled up with Chevron 91 octane, so I ended up with a tank of 88-89 octane before I set out on the trip home. I saw about 46 mpgs for the first 310 miles home, and pulled into the Chevron station in Frasier Park and filled up with 91 octane again. So, I now had a full tank closer to 91 octane. I continued home the remaining 115 miles in fairly light traffic, even through LA, and saw these phenomenal numbers when I pulled into my driveway: 67.7 mpg over the last 115 miles!!! Also, I didn't know the car had a 14:1 compression ratio!
BTW, I've seen the term "lift and coast" used in many fuel efficiency threads - what exactly does this entail?
