Miller makes a case for Toyota's support of parallel hybrids by saying that at this point the Volt is vaporware, while you can buy a Prius today. He notes that Volt engineers are only able to get about 10 miles of pure electric range from current lithium-ion batteries, far short of the 40 miles promised by GM. He also goes after the set up of a series hybrid, saying, "So – and we love this part - a series hybrid hauls around a gas engine that isn't available to directly propel the car."
There are no doubt engineers in this audience who will read Toyota's response and rip it to shreds, much like commenters have already done on the original post. We'll merely respond to two points, since we're not engineers. Toyota calling a series hybrid vaporware because there isn't one on the market today is bunk. We assume the Hybrid Synergy Drive was at one time in development, too. While there's certainly a chance the Volt may never happen (10% according to Bob Lutz), the fact that GM is already using the Volt in advertising and has been completely transparent with the car's development tells us that it will do whatever it takes to bring this car to market.
To actually question the efficiency of a series hybrid versus Toyota's parallel system also comes across a bit like sour grapes. While one can argue how clean a car really is that relies on the national grid for electricity, our measuring stick for the success of a green vehicle is how little gas it uses. Sure, it's simplistic, but it not only addresses the general greenness of a vehicle from the perspective of a consumer, but also how much money it will save its owner at the pump, as well how much it will reduce this nation's consumption of oil in general. Point blank, a series hybrid's gas engine (if it employs one) is really a generator, and it's optimized to run at a constant speed with a constant load. However much gas a series hybrid does use, its generator will use it much more efficiently than the engine in a parallel hybrid that has to be powerful enough to drive the wheels.
Aside from taking issue with Toyota's defense, we also read a lot of fear between the lines, a state in which we rarely ever see Toyota. Its reputation as environmental and technology leader is under attack from all sides, and GM of all companies is leading the charge. At the moment, no one doubts the dominance of the Prius and its capabilities, but before too long the green car market will change dramatically. Not only are we promised plug-ins, lithium-ion battery packs and a series hybrid, but new clean diesel engines will be along shortly and likely achieve similar if not better fuel economy in the U.S. than most parallel hybrids. That's because we like to travel on the highways of America more than in its cities where parallel-friendly stop and go driving is standard. Diesels are more efficient at cruising speed, more so in comparable applications than any gas/electric parallel hybrid on the market today. Frankly, we can't wait to see how all this goes down in the next few years, as surely the green conscience consumer will be the ultimate winner.