Of course, there are many ways to reduce the rate (as you mention), and of course, the government has made such modifications illegal.
My proposal is to measure the emission rate, multiply it by the mileage driven in the last year, multiply by the tax rate, and pay the tax to renew the license.
It's not perfect, but it's simple and a far better approximation than the existing brain-dead method. Instead of incentivizing drivers to just pass the test, they are incentivized to minimize the total pollution their driving emits.
In this case, “I” was intended to mean an automotive engineer working to comply with a government ppm-metric-driven regulation, not an end consumer, but my words were definitely ambiguous on that topic.
My proposal is to measure the emission rate, multiply it by the mileage driven in the last year, multiply by the tax rate, and pay the tax to renew the license.
It's not perfect, but it's simple and a far better approximation than the existing brain-dead method. Instead of incentivizing drivers to just pass the test, they are incentivized to minimize the total pollution their driving emits.