City of Yuma experiments with hybrid vehicles

Charlie Caudill
Equipment Maintenance Superintendent
City of Yuma, Arizona

The City of Yuma is in a unique situation in that we are not in an area that is affected by mandates to have alternative-fueled vehicles in our fleet. However, we have taken a different approach and have decided to experiment with alternative-fueled vehicles to enable the city to develop a database on what will work and what will not.

After checking on what was available, the City of Yuma made a decision to purchase two Toyota Prius hybrid vehicles. The Toyota Prius utilizes both gas and electricity for motivation. The vehicle systems are integrated to provide seamless performance. The gasoline engine supplements the electric motor for acceleration and for highway operations. The systems work together to provide all functions that would normally be seen on a vehicle such as air conditioning, power brakes, power steering, and power windows and door locks. In fact, this vehicle has all of these features as standard equipment.

Toyota states that these vehicles will average 50-55 miles-per-gallon (mpg) for city driving and 40-45 mpg during highway operation. Our experience so far has been an average of 43 mpg highway and 48 mpg city driving. These figures are dependent on who is driving and whether or not the air conditioner is on.

The Toyota hybrid system utilizes on-board battery power as a primary power source up to about 20 miles per hour. Then the gasoline engine provides additional power to help motivate the vehicle up to speed.

The car has an on-board computer system that monitors the vehicle's propulsion system and makes the necessary shifts from gas to electric and back again, all without a change in vehicle operation.

The dash has a monitor screen that displays the entire drive system and displays which system is operating at what time. It also has a display which tracks and records average miles per gallon and updates every five minutes of operation. This monitor, at times, can be a distraction, in that you can be fascinated by everything going on and can cause the driver to not pay attention to the road.

The Prius is basically designed and built on a Corolla platform, with ample seating for four adults. The trunk space is fairly large for a vehicle that has a battery pack in it. The air conditioning system is very good. The vehicle has a constant velocity transaxle that operates very smoothly.

With this type of technology, the City of Yuma believes it can increase its fleet fuel mileage and reduce emissions at the same time, without a huge outlay in expense.

For more information on the City of Yuma's experience with the hybrid vehicles, please contact Charlie Caudill at 520-343-8716 or at