Hi, I'm not a French teacher but a french native, so I assume that I can help you here! In French, the sound "o" can be written in different ways : o, ot, au, ault, eau. It's like this. I can't explain the reason but it's like a grammar rule. Hope it helps... Good luck with your French language learning!

Bonjour, En Français, on apprend que les noms propres n'ont pas d'orthographe or "Renault" est un nom propre !