How do I get more fuel and smiles?

Fuel

Fuel recharges automatically (5 units per hour). Max capacity is 50, and after that, it stops charging. You can also buy fuel for a certain amount of gems in the in-game store.

You can also watch videos to receive free fuel.

Smiles

You get smiles for quickly serving passengers (depending on the order size), taking back Trays, and serving optional items.

Once you have collected 350 smiles, you can exchange them into one gem by using Smiles Button.

Note: below we have an image showing where you can find the option to watch a video for fuel or smiles: