Can you actually save fuel by coasting. Taking your foot off the gas and coasting down a hill and half way up the next?
I really don’t know. But would think any savings by coasting uphill would be lost as soon as you try to regain speed lost.
Every time you coast, you are saving fuel. Every time you coast, you are slowing down and upsetting the folks behind you.
Just remember, don’t do this in neutral. Leave it in drive, there is an over running clutch that allows freewheeling. If you don’t understand this, google it. Just don’t coast in neutral, it is dangerous and won’t save you any fuel.
Physics: going down hill uses less energy than driving on level. Going up hill uses more energy. The more the gas pedal is depressed, the more fuel is called for. The faster the Pistons move the more fuel is used. Saying all that, as long as you drive with common sense you shouldn’t have a lot to worry about.