Mountains and Fuel Economy

I haven't seen a BSFC chart for your Gen4. But on the Gen3, any peak "sweet spot" is very small, the engine is tuned and operated quite close to maximum efficiency over a very wide RPM band.

Gen2 has a bit more pronounced and narrow peak efficiency, but even its version is short in height and fairly broad in RPM compared to traditional non-hybrids.

 

BSFC map for Gen 2 and Gen 3 compared:



The 2ZR-FE in the Gen 3 has a larger and more efficient "sweet spot" than the Gen 2, like you said; I seem to remember from the press release that Toyota said the reason they went with a larger 1.8L engine was because the higher torque output let them run at lower RPMs for the same power but better efficiency at a given speed. I would imagine the Gen 4 is similar since it's basically the same engine.

 

I'm portraying it as a very broad, nearly flat plateau, not a narrow peak. Almost any operating condition from a bit above idle speed, up to roughly 4000 RPM, counts as being in the "sweet spot". Pulse & Glide counts on finding and getting in to a sweet-spot peak that is not being used in normal cruise.

I am presuming that Gen4 is a least as good as Gen3. I'm actually hoping for even better, but don't recall seeing anything showing it.

 

Between August 18 and August 23, I went on vacation from the San Francisco Bay Area (specifically Oakland, CA) to the Eastern Sierra of California. I've posted images of my dashboard stats when I returned here. The trip involved driving from Oakland over Echo Summit and Luther Pass to Minden, Nevada. The next day, I drove to Mammoth Lakes, CA. I spent two days based in Mammoth Lakes at about 8,000 ft above sea level. I then took two days August 22 and 23) returning to the bay. The first day, I summitted the Sierra at Tioga Pass (9,941') and ended the day in Groveland, CA (about 3,300 ft). I finished the return the following day. Overall mileage for the 656 miles traveled was 54.9 mpg.