Does anyone know the origin of the word, and what it means in French? Also, it says on Dictionary.com it's sometimes pronounced as 'ruh-nawlt' - can anyone give an instance of this?
According to wikipedia, it comes from its founder Louis Renault.
When its cars were exported to the United States during the 1950s and 1960s, the name was commonly mispronounced as "Ren-alt" to and by the American public, and the Americanized pronunciation continues in common usage, though the original French has gained significant ground over recent years.
Presently in the United Kingdom it is also incorrectly pronounced as "Reh-no". The correct pronunciation is "Ruh-no".
The original name would have been Raginwald - counsel ruler - from which English gets Reginald. It's a German name originally. Same origin as other French surnames like Renaud, Reynaud., Reynault. At the point at which surnames began to be fixed these families became known by the first name of their father or an important ancestor. It's the same process by which English gets surnames like Jackson, Jacks, Jack, Jaques, James etc.