I found out the hard way that even though the dash still says it has 80km to go until empty, my car will not start if parked on a steep incline. I live on a hil

I found out the hard way that even though the dash still says it has 80km to go until empty, my car will not start if parked on a steep incline. I live on a hill of course. Unfortunately I ended up learning this lesson twice because I'm a dummy who needs to test boundaries. But at least I had the jerry can from the first time on the second occasion.