Toyota has just released more details about the changes that were made to the recently unveiled 4th generation Prius (we saw spy shots before the official launch!). They are impressive from an engineering standpoint, but looking at them, I can't help but think that they are a sign that we're nearing the end of the road for what is possible with a gasoline engine.
Changes to the Prius
Everything has been redesigned, rebuilt, rethought, optimized and streamlined (all the details are here)... And the overall efficiency improvement is expected to be 10% (the previous generation Prius had a rating of 50 MPG in combined driving, and this one is expected to be around 55 MPG). Doesn't that seem like a lot of work for 10%? Don't get me wrong, it's great to squeeze out more out of every drop of fuel, and Toyota sells a lot of hybrids, so any improvement is multiplied by a large number (since 1997, Toyota has sold 8 million hybrids, saving 5.8 billion gallons of gasoline).
But if I had been in charge of created the 4th gen Prius, I think my top priority would've been to make it plug-in by default. Even if you can't make the battery much bigger to keep costs down, adding the ability to top up the battery from the grid would've no doubt made a much bigger difference than the 10% that Toyota got out of the other improvements. Even if the relatively small battery can only get you 10-15 miles of pure electric driving, that's enough to make a big difference for most people who frequently drive short trips. And every couple of years they could make the battery a little bigger while keeping price constant, as battery prices fall.
Powering the Engine Efficiently
Right now with a regular Prius, 100% of the electricity that goes into the battery comes from the gasoline engine (directly or indirectly, via regenerative braking). If you could plug-in, some people would charge up with clean energy (wind, solar, hydro), making a portion of miles driven have minimal impact. And even those who would charge from a grid where the power comes from a mix of dirty and clean sources would see benefits since power plants are more efficient at turning fuel into electricity than a gasoline engine is, and over time, the grid is getting cleaner thanks to the renewable energy revolution.
So Toyota could have the regular plug-in Prius as the least expensive option in the lineup, then a more expensive plug-in Prius with a much bigger battery, and then over time as battery costs go down, they should eliminate the tiny battery version and only keep the other, and make a fully electric Prius to sit at the top of the pyramid.
I think that would be a more effective strategy. Less timid, for sure.