One way of gauging the improved efficiency is the following:

In my previous vehicle, I put in approximately 10 gallons of fuel after 300 miles.

In my Prius, I generally put in between 8 g./400-425m and 9 g./450-475 m. (I haven’t tried emptying the tank more than that, since, I don’t need to, and long-time drivers don’t recommend it.)

I consider that a significant difference. And it looks to get better with the onset of spring.

First: I do not consider myself an environmentalist. I don’t think anthropogenic global warming is real (at least, not a real problem). I did not buy a Prius because I want to feel good about myself or show off.

I am an adjunct college teacher, teaching at 6-8 courses a semester, 3 different campuses. Typical mileage is 350-400 miles a week during school. I got tired of filling up every 4-5 days (and that in a car that got 29-30 mpg).

As others have said, the kind of mileage depends on how you drive. Most of my driving is on roads where the speed limit is 55 mph or less, and I do not go more than 2 or 3 mph above that. On 65 mph roads, I go between 55 and 60. Of course, I use cruise on limited access roads.

During winter, I got above 45 mpg, and, if it was not too cold, approached 50 mpg. It has just warmed up, and am presently getting (according to instrumentation, which is usually slightly inflated) 57-58 mpg. It appears that the optimum outside temperature for maximum efficiency is above 50 or 55 F.

I take it easy uphill and coast downhill. One learns to anticipate traffic, slow down if there is a red light ahead, etc. It has made me a more patient driver, which I think is a good thing. I don’t get as anxious if I get behind a slow truck, since I know that will actually improve my mileage. I realize I paid a price premium for the car, and intend to maximize the technology. For those who are willing to do that, the Prius is excellent.

The Prius is a very nice car. It is a pleasure to sit at a light in silence. The push button start is handy in winter–no fumbling with the keys. I’m sure it doesn’t have the ride or driving characteristics of an Accord or Camry, but that is the price I pay for approximately doubling my mileage. Now that gas appears headed back to $3/gallon, I am very happy.

Use of a battery or dynamic braking to charge a battery does not a hybrid make. A hybrid switches from gasoline to electric propulsion for different power requirements. Diesel-electric power always uses an electric motor to drive the vehicle. There is nothing radical or hybrid like in this technology.

Sounds like it will be sold based on additional pulling power (temporarily drawing power from batteries as well as generator) as well as the fuel economies and reduced emissions.

The diesel-electric locomotive is not a hybrid. The diesel engine turns a generator which powers the locomotiveís electric motors. Diesel-electric power is best used to propel large vehicles and ships. It was first used on US Fleet type submarines in the 1930ís. Before the development of the modern diesel-electric submarines Diesel power was limited to small to medium sized vehicles like switch engines. A historical note for technophiles the Fleet Submarine doomed the steam locomotive because it led to the development of a better technology to pull trains. Oddly enough the Soviet Union did not use diesel-electric power until the Kilo class submarine. Previous boats had separate diesel and battery powered propulsion systems. These systems were more like a hybrid automobile then diesel-electric locomotive. The last class of US diesel subs, the Barbel Class (SS-580) refined the process one step further by always running the motors off the battery and charging and discharging as required.

Hybrid technology for cars may not represent a good economic tradeoff at this instant in time, but it is subject both to manufacturing economies of scale and to further development. The envirosnobs now buying hybrids may actually be doing us all a favor by moving the technology further out the learning curve.

Also, hybrid drive and diesel engines (for cars) are not necessarily opposing technologies; there’s no obvious reason why they can’t be combined.

Hybrids are not the stuff of magic. Nor are they mere snake oil. What both the boosters and bashers need to realize is that hybrid technology is not meant as a revolutionary advance. It is simply a refinement of the same internal-combustion-powered drivetrain we’ve had in our cars and trucks for more than a century. But we believe it is an important refinement–especially for larger, more fuel-hungry vehicles.

Ultimately, today’s hybrid systems will be replaced by an entirely fossil-fuel-free powerplant. But for now–and by “now” we mean the next decade at least–we think hybrids make sense. Not for every vehicle or for every driver, but perhaps for a larger group of drivers and vehicles than either boosters or critics now recognize.

You are correct about one thing. No car other then a Diesel gets it EPA rated mileage. The technical reason for this is that the EPA uses a technique that measures gas mileage by using the weight of emissions over some time period rather then by driving the car in normal use. This is why hybrids have vastly inflated gas mileage. On the test stand they use battery power optimally and thus reduce emissions weight. This technique underestimates diesel efficiency because of the soot produced in heavy fuel combustion. The Jetta TDI gets an EPA rating of 44mpg but in use itís closer to 50mpg.

Toyota and Honda have correctly judged that if you call something green you can get Americans to buy inferior technology for fuel economy. Neither Toyota or Honda produce diesel engines so they have developed a marketing strategy that uses their well earned reputation for quality and inovation to scam green minded consumers.