You can't have perfect security. You can have security that makes bad actors pay more for the privilege of being bad actors.
Or whatever - the point isn't the methods, it's the pattern of one-upsmanship.
Hell you could put a green odometer in it and give a tax break proportional to the percent of miles driven in green mode to encourage it's use.
Trying to force car enthusiasts to give up performance will just drive them to older cars which don't have crippling software or dangerous hacks to bypass the restrictions.
So, say I want, for instance, to represent the stereotype person who rolls coal on their diesel pickup and believes global warming is a left-wing conspiracy. Look it up on youtube if you don't know what rolling coal is. (We can get into a whole debate on whether stereotypes are inherently good or bad, but that's not the point. They're a very effective commumication tool, which is why humans are so quick to label and group other humans, but obviously they're only to be used when not offensive.)
And I suspect that a luxury performance car owner would be just as likely to turn off emission controls if it would help performance as a rural pickup truck owner of whatever political persuasion (in both cases).
If we're trying to avoid gaming the system, wouldn't it be better to drive around a bunch of cars, using the natural variability of the conditions to defeat the cheaters? Sure, it's not as precise, but you get better accuracy because people can't trick the system.
And also, how will you ensure that certain manufacturers aren't actually given better conditions?
You look at them with disbelief and ask why they designed it to skirt the edge of illegal levels of pollution and be so likely to fail.
For CAFE, makers sell some high mpg models at cost/slight loss to allow them to sell high-margin luxury and sports models.
I suspect that in a few decades time this will be regarded as a heavy blow to the internal combustion engine - or at least against Diesel. It is an inflection point at which a scandal pushes into public conciousness and mass media the mounting evidence against Diesel engines and the health effects of smog, and the insufficient actual progress fixing it. Meanwhile electric cars are gaining fast.
The politicians are in "something must be done" mode, which is the usual reaction to a problem that has been ignored for a while and now is in the news.
e.g.
https://uk.news.yahoo.com/france-consider-phasing-diesel-tax...
http://uk.reuters.com/article/2015/10/03/uk-volkswagen-emiss...
http://www.theguardian.com/business/2015/oct/01/uk-governmen...