Drive Unwisely and the 2023 Prius MPG Drops To This Low Value

The all-new 2023 Toyota Prius is fantastic. It is quick, fun to drive, really attractive to look at, and surprisingly roomy. Toyota’s new for 2023 infotainment system is perfect. Ideal. Exemplary. We are running out of good words to use. But if you don't mind your manners, what’s the real-world MPG? We torture-tested the new 2023 Prius to see how low we could force its MPG down. The result stunned us.

We first dropped the rear seats, removed the cargo privacy cover, and loaded the Prius up from the floor boards to near the roofline, including the passenger seat front and passenger area floor with all the heavy stuff we had been planning to haul to a mountain cabin in New England in a big-tough SUV. The first surprise was we had room to spare

It was a hot, muggy day with temps around 80F and humidity around 112% (Yes, we know). So we cranked up the AC to full blast during the entirety of our trip. And when the speeds were under 45 MPH, and it wasn’t raining, we dropped all of the side glass. Hey, why not leave the AC on as well? And the headlights and the seat coolers. 

Next, we engaged Sport mode. Maybe the Sport Mode would shed a few MPG. Since we had Sport engaged, we opted to drive in a (safe) manner that would give us the most thrills possible without risking a chat with the local constabulary and more points on our insurance. At every stoplight, we floored it. Every incline, we floored it. Open road ahead offering a higher speed limit? You get the picture. We floored it. When it was time to stop, we didn't glide to let degenerative braking be maximized. Nope. We came up fast to the stop and used the friction brakes - hard. In other words, for about an hour and a half, we drove like a dummy.

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Short of throwing out an anchor, we did everything we could think of to burn up some liquid sunshine and give the hybrid naysayers exactly what they desire - Proof the Prius is really not all it's cracked up to be. 

Our observed MPG after 70 miles of these shenanigans was 55.0 MPG. That’s three MPG higher than the EPA-estimated fuel economy. In the case of the Prius Limited trim, the EPA estimates the fuel economy of the Limited with its big 19-inch wheels to be 52 City, 52 Highway, and 52 Combined. So 52 MPG ALL THE TIME. 

Our route was about 25% highway with a speed limit of 55 MPH to 65 MPH and a lot of 45 MPH and 55 MPH mountain roads. During the start of our trip, the MPG on the highway rose to as high as 59 MPG. During long, steep mountain inclines in the middle of our journey, it dropped to as low as 48 MPG for a few miles, only to rise back up again as the other side of the mountain offered a decline. These are not instantaneous MPG readings but the accumulating MPG average, which we zeroed when the vehicle was dropped off by our media fleet managers (who are fantastic).

Related Story: 2016 Prius Exceeds MPG estimate on long highway trip fully-loaded

There were no tricks; The vehicle came full of Regular 87-octane liquid sunshine. Its tire pressure was within one psi plus or minus the recommendation on the driver’s door jam. 

Is our test scientific? Not really. However, if you are going to call the Environmental Protection Agency and Toyota a liar, do so with your own proof. Based on our testing, in the worst possible circumstances that anyone who buys a Prius is likely to use it, the car exceeded its MPG claims. As an added bonus,  it is a fun car to drive, even when loaded with hundreds of pounds of cargo. 

Postscript: On the return trip, empty of cargo, driving like a grown-up in Normal Mode with AC off and windows down most of the time, we observed 59.6 MPG. 

Image of 2023 Toyota Prius with full cargo area by John Goreham. 

John Goreham is an experienced New England Motor Press Association member and expert vehicle tester. John completed an engineering program with a focus on electric vehicles, followed by two decades of work in high-tech, biopharma, and the automotive supply chain before becoming a news contributor. In addition to his eleven years of work at Torque News, John has published thousands of articles and reviews at American news outlets. He is known for offering unfiltered opinions on vehicle topics. You can follow John on Twitter, and TikTok, and view his credentials at Linkedin.