My Prius ran out of gas today, and I got stuck on the side of the road. Let’s put aside the too obvious irony of a hybrid running out of fossil fuel for a moment. This post isn’t about irony. This post is about embarrassment.

This was pretty much the most embarrassing thing that has happened to me in a long time. Embarrassing because my wife, daughter and friend were all trapped in the car with me. Embarrassing because I had just intentionally driven past a gas station a few minutes earlier. Embarrassing because the Add Fuel message had been coming up on the dash display for the past two days.

I love my 2007 Prius. It gets 45 to 48 miles per gallon, drives great and is very comfortable. I also love my Prius because the dash display provides real-time analytics. I’m a sucker  for charts, bar graphs and real-time data calculation. While driving, my Prius shows a bar graph of the average estimated fuel consumption. This is a bar that escalates up to 100 MPG from 0 MPG. The more you coast, the more the electric motor carries the car and the lower the fuel consumption, which means higher gas mileage. Every five minutes a new plot point appears on the elapsed drive time chart that shows the average gas consumption over the life of the trip. At the bottom of these lovely graphs, is a real-time numeric average of miles per gallon over the life of the trip or the tank of gas. I generally set this to reflect the average fuel consumption for the current tank of gas. Like I said, 45 to 48 miles per gallon.

When I fill up, I zero the gas mileage calculation and also the odometer reading for Trip A. I reserve Trip B for mileage between oil changes. The 2007 Prius has an 11.9 gallon gas tank.

Generally when I start the car on a low tank of gas, the Add Fuel message appears and then disappears. This occurred on Friday. I didn’t worry about it right away because I can drive many miles on just a little gas. No worries.

When my gas indicator gets low, I do a little math. I glance at the average gas mileage for the current tank of gas, then multiply by 10. Then, I add the average gas mileage to that number to get the number of miles I should get from an 11 gallon tank. I subtract the miles showing on the odometer from the estimated miles for 11 gallons of gas to figure my zone of safety.

Today, when I passed the gas station on the way into town, I estimated an additional 15 miles before getting close to Actual Empty. I thought I would do my town a favor and give them the sales tax on my fuel purchase.

My car slowed down, sputtered and stopped about five miles past the last gas station. I was completely baffled. My math was good. I should have had at least another 10 miles or more before needing to fill up. Math doesn’t matter when you are stuck on the side of road. Or maybe math matters more than you care to admit when you are stuck on the side of the road. In either case, I called my mom-in-law to stop by the house to get the gas can, then deliver the mercy gallon we needed to get to the gas station.

Rather than wait on the side of the road, my friend and I decided to push the car to a parking lot not far away. As often happens, while pushing the car, a couple of other guys stopped by to help push. We got the car to the parking lot easily enough. The guys offered a spare gallon of gas from their emergency tank but we already had help coming so we declined.

They laughed a little about pushing the hybrid, climbed into their big, fuel-thirsty pickup and drove off.

My mom-in-law showed up pretty quick, we gassed up and drove to the gas station for a complete fill. No harm done and no real danger.

I learned few valuable lessons.

First, the Prius actually holds 11.9 gallons but you only get to use a little less than 10 gallons of that because a certain amount of gas gets caught in the fuel filter and fuel lines.

Also, my five-year-old daughter enjoys the opportunity to lecture me about the importance of paying attention to the messages on my car display:

Finally, I can see that the major lesson here is one of choosing where to place your attention. I was, after all, paying very close attention to the graphs, charts and numbers on my dash and was using an overly complex, sophisticated system to determine when I needed to refuel. Math is powerful, but when your car display tells you to Add Fuel, it isn’t time to argue. Best to keep some things simple. Sometimes, you should just receive the message, say thank you and fill up.