Cola

From OpenTTD

In OpenTTD, cola is the flat version of the popular drink of the same name. It is obtained from cola wells, which due to their mysterious and somewhat comical-looking nature of course only appear in the toyland climate. The cola is then transported to a Fizzy Drink Factory in order to have the bubbles put in and thereby be made into the more recognisable sparkling beverage.

Being a raw ingredient, cola is transported by tankers - it is only canned at the Fizzy Drink Factory.