I had a warning come up about parking assist failure. Having looked in the handbook, it does say that they should be kept clean so I guess all the dirt thrown up in the current weather is stopping them working properly. Unfortunately, I have found that rear sensors didn't work properly about a week ago when I backed into a telegraph pole, with no beeps sounding. I was going very slowly, so no damage. But it shows that you can't rely on them.
Haven't had any problems with the fuel guage, but usually put about £50 worth in.