Coca vs. cola

"Coca" is a registered trademark and widely used in France for the abbreviated reference to the ubiquitous beverage. As also often happens in English, some brand names become synonymous with a 'product' in general, and the word enters the general lexicon. It is not uncommon colloquially in France to be asked if you want ' un coca', instead of being offered 'une boisson'. Coca (as for 'coke') in English has other traditional meanings https://www.dictionnaire-academie.fr/article/A9C2719

Pourqua ce coca et non cola. Parce que centers un marque registre