To get up a hill you have to input the energy based on m*g*h. Note how time isn’t part of this equation.
The losses that you can affect by speed are wind and rolling resistance. Both of which go up as your speed increases. So slower is better.
…to a point as there are consumers in your car that are independent of driving. E.g. your AC/heater, lights, and simply keeping the cars computer running also draws some power. So there is an equilibrium point where crawling even slower will no longer save energy.
What’s the difference between ‘rarely’ and ‘not so often’?
You should not ask qualitative questions in surveys as they are open to subjectivity and therfore do not result in good data. You need to ask quantitative questions (like “once a week”, “once amonth”, “less often than once a month” etc. )