[quote=“lateracer” post=62106]The longest possible enduros I can imagine doing are the 24hour runs. Most of the races are Lemons/Chump Car, which are about 7 hours per day (working my way to Spec one day). Sometimes things go smoothly and fuel/driver changes go according to a predictable schedule. Most of the driver shifts are about two hours, but sometimes they can run near 3 if we have several of “unplanned” stops early on.
I spend my work days deciding what does or doesn’t go on a screen someone’s using for a specific task that requires most/all of their attention. I’ve noticed the same problems that show up in those circumstances show up in a race car. Specifically, drivers who don’t know the car that well sometimes miss important lights/gauges in the heat of the moment…like the oil level light… so I’m also looking to get the factory cluster out from behind the wheel. The end goal is to provide an environment that allows me to say “If any red lights blink or you hear a buzzer, something needs attention quickly”
Dgorman, thanks for the heads up about damping and calibration. I’ll throw some debounces or pauses into the coding to damp the reading process. I assumed the resistance reading was linear. My tank is getting near empty, so I’ll plan to drain it and take readings at 1 gallon increments when I fill it.
I could see how other people have actually used arduino for this and not posted about it before. It’s pretty easy. All the code you need for both the fuel gauge and a speedo comes with the software.[/quote]
Make sure it’s truly empty… You might waste a lot of calibration time thinking your tank is 100% empty when it’s not 
unless you already had a DAC shield, but was still 8bit)