And the pause between them. In a four letter word, I'd say that's quite different. Would you have read it as "no va"?
There's no pause between both syllables in either way of pronouncing the word. And you are right, it's not pronounced the same way, but if you intend to mock the car, you just stress the other syllable.
Stresses are pretty important in spanish. Take father/pope and potato; viva la paPA has a pretty different meaning from viva la PApa