Things are never as they seem

Well, my last post told of the immersion going pop, and us having to replace it...................well!!

Of course, life is never easy...............when hubby went to change the immersion, we discovered why it went pop in the first place................top of the tank was corroded. So, £200 plus later, we now have a new hot water tank.

And while we are on the subjects of why things are never as they seem, can someone please tell me why full to half full on the petrol tank is more than half full to empty. Today, I got in my car to come home, and part way home I noted that I had done 300 miles since I last filled up. When I filled up, the petrol gauge read 3/4 full. At the 300 mile mark, the petrol gauge was on 1/4 full. This was what is was on 13 miles later!!!!

How come 3/4 to 1/4 is 300 miles, and 1/4 to just above empty is 13 miles???