How to get max power in Prius?

At 75 mph the Prius goes to peak power rpm automatically when you floor it.

Redline is past max power rpm on nearly all cars. If you are redlining the engine, you are producing less than max power.

 

The interstate here has a speed limit of 75mph. I routinely drive at 80mph.

I do not see any 'need' to pass anyone at those speeds.

I do pass other drivers who are driving slower. But why pass someone who is already exceeding the posted limit?

 

The software attempts to give you the power (in most cases, actually torque) you request with your right foot.
The HSD (Hybrid Synergy Drive) or PSD (Power Split Device, the hardware the computer's software is controlling)
Toyota Prius - Power Split Device These is a nice Gen 1 Prius simulator down the page a bit. Actual details will vary, (Gen 3 has a 5200 RPM red line for example) but the principles are the same.

M/G2 (Motor/Generator) is geared right to the wheels, so as you rev M/G2 you can select 70 MPH.
You will notice that the line connecting M/G2, the ICE (Internal Combustion Engine) and M/G1 'breaks' and turns red. This is because you can't go 70 MPH with out turning on the ICE, so lets rev it up to about 1300 RPM so the line is not 'broken' and red.

Now you can play and see that by altering the ICES revs between 1300 RPMs and red line, M/G1 varies between 6500 RPMs turning the same way as M/G2 and the ICE, to 6500 RPM going the other way. (The software actually controls M/G1s RPMs and the throttle for the ICE, your foot on the accelerator is just a suggestion)

On my Gen 2 I could see the ICE rev with an accuracy of 6 RPMs, that is a lot of choices. If the ICE can make the power, the HSD can find it. In my Prius,a constant 70 MPH on a flat road is near 2050 RPM. Different models and generations will vary.

Electric motors often produce maximum torque at 0 RPMs, sl it helps the Prius at low speeds a lot, not so much at high speeds. (This is a generic curve, not the actual Prius M/G2, the starlight line is torque, the curved line is power))


I suspect the Prius ICE is artificially held to a low red line, the Otto equivalent engine has a red line of 6000 RPMs as an example.
Toyota ZR engine - Wikipedia, the free encyclopedia

 

The Gen 2 and 3 Prii don't put out any more power if you spin them faster, so no point in spinning them faster.

That is part of the reason I said "nearly all cars".

 

Gen3 ICE max out at 5,200 RPM. The only way to get rev that high is with your right foot.