My apologies, I made too rash a statement. Actually, yes, the US is a worse offender in emissions as a country.

However, I live in California and for individual vehicles, I think Cali has the most stringent emissions requirements for individual vehicles. JDM vehicles don't pass emissions testing here. (And we also have crappy low octane gas.)

Let me say instead, I'm not Nihon because I need a left hand drive car.