Cut auto emissions by 50%

I propose a law that mandates that anyone who doesn't have a "job requiring larger vehicles", i.e. transporters, construction workers etc. be limited to driving a 4 cylinder (or less) vehicle. This would CUT AUTO EMMISSIONS IN HALF, RIGHT NOW, AT NO COST.
The same way you need a special license to drive an 18 wheeler, you will need proof at purchase, or DMV owner transfer, that you have a business that "requires larger vehicles". Dealerships can still sell their large vehicles to those customers, but the "forced demand" for 4 cylinder cars would create jobs producing more of them, and less fuel consumption equals less demand, which equals lower prices. Not to mention the environmental benefits. The only cost would be to legislate the law. I know republicans will oppose anything which leads to less oil consumption, as they demonstrated, when they were in control, by blocking any increse in the fuel economy standard. They, apparently, don't care about their own children and grandchildren, clean air, clean water, uncontaminated soil, and, what they call, unimportant things like that.
I am also well aware that Americans don't want to compromise or sacrifice ANYTHING, EVER. These (ridiculous) facts notwithstanding, I implore you to act upon this proposal immediately.and enact this much needed, and sensible, law.