Considering we DON'T know what kind of motors are used in the cars that's a HUGE assumption. It is entirely possible that they use a micro reactor to power an electric motor with turbine blades for cooling.
This is SciFi bud, anything is possible. Hell Lucas had the Naboo large transport sound like a transport truck's engine brakes in SW Ep2 for God sakes! Until some definitive technical info is given on the cars, it's fine as it is.
BTW, you might want to loose the "j*ps" term as it isn't any sort of term of endearment regarding the Japanese. Racial slurs are not tolerated on these boards and you might find yourself on the business end of a moderator smack down...
Again, attacking other posters for a difference of opinion is not helping your rep around here. Until something is actually revealed in a story it is considered speculation.
I may agree that Agent G is indeed Grace, however I respect the opinions of those who don't share my belief. Try it, it keeps people from ignoring your posts as some sort of forum troll's keyboard diarrhea...
You are entitled to your opinion, however I disagree...