Even a meager 2% reduction is about what $10,000 in fuel savings??....
If you spend $50,000 a year on fuel, which straight trucks have been known to do, a two percent savings is $1,000 per year.
So, to calculate the payback on such a device, you need to know:
- Cost of device
- Cost of down time to have device installed
- Cost of deadhead miles to have device installed
- Anticipated useful life of the device
- Maintenance and repair costs associated with the device, if any.
- Tax depreciation schedule of the device.
- The present value of the total of all of the above.
You also need to be able to accurately measure the fuel savings that are specifically attributable to the device, which is a very tricky thing to do, if not impossible, because of all the other variables involved. And the measurement must be taken over a meaningful time period and number of miles.
For example, we have noticed that when our tires wear down, fuel economy improves; not be a lot, but by a noticable amount. We have also notice that fuel economy improves in certain seasons of the year, and at certain altitudes.
We could add a device in August, happen to be running with tires that are near the end of their useful life, happen to be running more than usual in low-altitude states, and happen to run for say three months in cooler weather. Without the device, we would show a fuel economy improvement probably greater than two percent with those variables in play. But if we were not careful, and not honest, we might be tempted to look at the first three months of numbers with the device, compare them to the previous three months and the previous year, and allow ourselves to believe that the device itself produced a two percent benefit.
I'm not suggesting that the device has no benefit. Indeed, the opposite is probably true. But with all fuel-saving devices, I am leery of the sales claims, careful to avoid self-deception, and careful to include all costs.
The bottom line is, how much money do you want to put into your truck and tank (additives) to boost your fuel economy, and how much is it worth it to you (including the non-financial benefits) really?