Current Issue

Power and Work

By Robert Roman


Ensure Their Most Productive Use

My wife has been complaining more frequently about my willingness to work — as in washing and waxing her car.

Work is said to occur when force results in movement. In the early 1800s, people used weight lifted through a height as a measure of work. Thus, an excuse for chores mightbe: “Honey, I’m older now and I don’t have the same lifting power.”

Power is the amount of energy consumed per unit of time. The rate at which a light bulb converts electricity into heat and light is measured in watts. The more watts, the more power or more electricity is used per unit of time.

Thus, another excuse for not washing the car might be: “Honey, I just don’t burn as brightly anymore and, besides, it’s really hot outside.” Like the lifting argument, this would go nowhere, so normally it’s off to the local car wash I go.

My decision to visit a car wash is to avoid physical work, which requires power. For example, a person hand washing a car may be doing work at the rate of several light bulbs or about 200 watts, whereas a trained athlete may work at a rate of 900 watts for short periods.

My electric-assist bicycle delivers 500 watts and goes up to 15 mph in no-peddling mode. The engine in the car I drive to the car wash works at a rate of 140,000 watts and it can go 120 mph. So, doing a lot of physical work requires a lot of power.

To illustrate how much work and power is involved in car washing let’s consider a charity hand wash.

When I supervised my daughter’s high school functions, I would arrange the kids in teams of two and set up stages for wash, rinse, and dry. Twelve cars an hour would usually take 10 kids and 14 when drying two cars at a time.

Fourteen kids working at 200 watts are 2,800 watts or 4 horsepower. Of course, after 70 or 80 washes, the kids have grown tired and interest wanes. By comparison, an in-bay automatic (IBA) washing 12 cars an hour may work at 50,000 watts or 67 hp. Moreover, as long as the juice is flowing, the machine keeps a grinning.

In short, machines can be designed to perform specific tasks better and faster than man at optimum efficiency — and machines don’t get tired.

If we sum up power delivered by equipment, a mini-tunnel might work at a rate of 80,000 watts, a larger tunnel 110,000 watts, and a still-longer one 147,000 watts or about same wattage as many automobile engines. Here, capacity is 50, 90, and 120 cars an hour, respectively.

Substituting labor for capital in a mini-tunnel, we would need 54 kids working at 11,200 watts or 15 hp to produce 48 cars an hour. Substituting an IBA for a mini-tunnel, we would need four machines working at 200,000 watts or 268 hp to produce 48 washes.

Arguably, units of measure, work, and power suggest kids may be better off promoting a charity car wash held at a commercial wash rather than actually washing cars, so they can spend time more productively like on their studies.

Likewise, some car wash owners might benefit from this approach.

Online products that repel water show customers are willing to pay a premium for protection — at cost of goods of $0.50 to $1.50. Products work mostly by manipulating the electrical charge on surfaces and are short-lived.

Consequently, some operators provide add-on service like express wax that contains kaolin clay to clean and polish paint and puts down a longer-lasting layer of wax or synthetic polymer. Service is usually delivered in 15 to 20 minutes by a team of two people. Sufficiently motivated, the team may work at 800 watts or about 1 hp to produce about three cars an hour.

Conversely, an automated vehicle polisher (rollover) may work at 14,900 watts or 20 hp to produce five or six cars an hour with one person. Here, the benefit would be charging $20 to $25 for service as compared to $3 to $5 for an online product.

In the final analysis, car wash operators often go to great lengths to tell consumers about how low their prices are. Hopefully, our little exercise shows operators should also consider telling consumers about the benefits of less work.


Bob Roman is president of RJR Enterprises – Consulting Services ( You can reach Bob via e-mail at