My Toyota Prius is a very good car that gets really great gas mileage. I own the 2001 model and the current models are even better. In the EPA’s old rating system, the 2001 model is rated at 51 MPG city and 45 MPG highway. I have been getting that or better most of the time. The 2001 Prius is also the only car on the road with a SULEV (Super Ultra Low Emissions Vehicle) rating. It is simply the cleanest car on the road – until the 2004 Prius which has a AT-PZEV (Advanced Technology – Partial Zero Emissions Vehicle) rating.
Here are some links to other interesting information about the Toyota Prius:
- Check out the 2004 Toyota Prius at the Toyota web site. It is rated at 60 MPG city and 51 MPG highway (Old rating system).
- Motor Trend Magazine named the Toyota Prius Car of the Yearfor 2004.
- Popular Science has named the Prius the Best of What’s New Grand Award Winner.
I have compiled a little information about how it works, and some very specific real world experiences that I have had with my 2001 Prius.
Two Power Sources
The reason for these seemingly backwards mileage numbers is that, in my opinion, Toyota got the technology right. By using an electric motor for low speed acceleration and cruising and a gasoline engine for highway speeds and more aggressive acceleration, the Prius gets the best of both worlds. and the best part for energy conservation and pollution is that the gasoline engine is turned off whenever it is not needed.
Electric motors have excellent low speed torque. In fact, electric motors generate their best torque from rest, thus making them ideal for starting the car from a standing stop. When accelerating aggressively, or when the engine has reached 1000 RPM, the gasoline engine is started to provide extra power.
I have been getting better than 50 MPG in city driving recently. This photo of the trip computer in my car shows that my current gasoline consumption for the last 263 miles is 52.5 MPG. Outstanding!
Strategies for Saving Gasoline and Reducing Pollution
One of the most wasteful times for any gasoline powered vehicle is idling at stoplights and very low speed travel such as in parking lots. At a stop light or sign, the car is getting infinitely bad mileage. It is possible to run a gasoline engine all day and never go anywhere, thus getting 0 miles per gallon while burning a full tank of gasoline.
This waste also extends to pollution. A car that burns gasoline while sitting still is polluting the atmosphere for a zero return in work, that is moving people or goods.
The Prius is unique in that the gasoline engine is turned off when possible. This includes time spent sitting at a stoplight and while cruising slowly looking for a parking space. I even find that my Prius runs on battery power only for up to several minutes at a time during low speed driving on surface streets – up to 30 and 35 miles per hour.
Another big waste of energy is that of braking. It takes a great deal of energy to set a car in motion from rest, or to increase its speed while accelerating. Check out Newton’s Laws of Motion for details. This energy is wasted when old fashioned cars brake to slow or stop. The energy of motion – kinetic energy – is converted into the heat of friction when the brakes are used to stop the car.
The Prius reverses the function of the electric motor while braking by turning it into a generator. The motor is used to capture the kinetic energy of the car and convert it into electricity which is used to charge the battery. This is called regenerative braking and it recovers up to 30% of the kinetic energy of the car.
Never Needs Plugged In
And speaking of the battery, you never need to plug the Prius into an electrical outlet. The battery is charged by regenerative braking and by excess energy produced by the gasoline engine while driving.
Although I have been getting better than 50 MPG in the city, the Prius is rated at 47.5 MPG at superhighway speeds, and I have found that to be the case in my experience with the car. Performance is affected by many factors, including your driving style, weather, traffic and terrain.
Long Trip Performance
I have shown some real world performance numbers for current city driving above. But two specific long trips that I have taken illustrate the range of performance you might get on the highway under differeing conditions. These two trips were significantly different even though they were both long distance.
One trip was 475 miles with 4 adults and the other was 850 miles with just my wife and I.
Tennessee, June 2002
472 miles at 47.4 MPG
This trip home from Crossville, Tennessee, was in June, 2002 for my father’s funeral. On the way over, it was just Alice and I.
Coming back, however, my daughter and her fiancée joined us. So we had four adults, five pieces of luggage, three laptop computers, one tower computer, all the miscellaneous small bags, snacks and other junk that accompanies four people on a long trip.
This trip was on I-40 all the way, through the North Carolina mountains. It was a hot day so we had the air-conditioner running. I easily maintained 75 and 80 MPH with power to spare to pass trucks on the uphill grades.
On this trip my Prius averaged 47.4 MPG. Part of the reason I got such good mileage on this day was that the engine turned off fairly frequently while we were going down the mountains.
I typically get around 47 MPG on the road in the summer.
Shenandoah Valley, August 2002
856 miles at 56.7 MPG
This was a vacation trip for our anniversary and was only Alice and I with our luggage. I was not allowed to take a laptop computer with me!
We took secondary routes and drove at a leisurely pace from Raleigh up to the Shenandoah Valley in Virginia. While there, we took several side trips. One was on the Blue Ridge Parkway, again at a liesurely pace, and a couple took us on I81 for about 150 miles.
Because the weather was mostly very mild, we were able to drive with the air-conditioner off for most of the trip. I actually achieved over 60 MPG during the first part of the trip. The whole trip was 856 miles at 56.7 MPG.
The Beach and back on a Single Tank
Long Beach, NC August 2004
578 miles at 53.7 MPG
This was our annual trek to the beach for a week. It was just the two of us, our luggage, beach chairs and umbrella, my laptop, and all of the paraphernalia that usually accompanies one to the beach.
It is about 175 miles from our house to the motel we stay at plus we did a good bit of driving around while we were down there. Our total distance was 578 miles with a consumption of 53.7 MPG. We actually did this on a single tank of gas.
I filled up Friday afternoon on the way home. We packed and left for the beach early on Saturday morning. We drove around all week, and Thursday night I did a little math that indicated that we should be able to get back to Raleigh without filling up. So we did. We got back Friday afternoon, and after unloading the car, going to the library to return books, and picking up the cat, only then did I fill up again. And the air-conditioning was on almost the whole distance between Raleigh and the beach and back – but not much while we were down there.