Replace the analog fuel gauge in your car with a more accurate digital version powered by Arduino.
Arduino Fuel Gauge:
A few months ago, I hit a pot-hole while driving my 1974 Dodge Dart and my fuel gauge immediately went to "E." For a split second I thought I lost all of my fuel! My father-in-law suggested I drive backwards over the pothole to fix the gauge. It didn’t work.
I researched some aftermarket options and I was generally unsatisfied with how they looked. Usually they were 3-digit 7-segment displays that read between 1-100 representing the percentage of fuel left in the tank. That style reminded me of the sad time in the early ’90s when car instruments were too digital.
I had one of them in an online shopping cart, ready to click "complete purchase" and sacrifice $50 and the analog soul of my car, when it hit me: "Hey, am I a maker, or not?" So I abandoned ship and decided to make a fuel gauge myself that would be cheaper and better than one purchased off the shelf.
Older vehicles usually have gauges that use a very simple analog circuit to read a resistance. You can read this resistance with an Arduino!