Let’s say you get 12 mpg, and fill up when you have on average 5 gallons left in the tank. Also assume you’re keeping the Jeep for 100,000 miles post-install.
That translates to 8,333 gallons of fuel burned through the remaining life of the TJ. That translates to roughly 595 fill-ups with the standard tank, or 427 fill-ups with the extended range tank.
Let us assume that the average fuel up time takes 15 minutes, including the time finding a station, decelerating, stopping, and merging, over simply driving past it.
That results in 168 fewer fill-ups through the life of the TJ.
As a result, you spend 42 extra hours of your life filling up the Jeep with the stock tank. If you value your time at $20 an hour, that essentially covers half the cost of the tank. Add in the convenience factor of not having to stop as frequently, and it eventually becomes worth it. In addition, the total cost also covers the cost of the skid plate, which many would otherwise spend several hundred to replace separately.