Some 40 years ago, there started an interesting (and easy to introduce) system with car registrations
On certain days only cars with even numbers can enter and on others only odd numbers
Now Rome, Paris, Mexico City, Bogota, and Beijing have similar systems with varying success
However it was not a perfect system
Delhi managed an almost immediate 11% drop in pollution levels. However where drivers would own a reasonable , they sold these and bought an evan and odd numbered banger - the end result being a 13%rise in pollution
Mexico City had less car numbers, so only prohibited the last digit - this was more successful as even buying a banger, having ten cars was not going to be possible
Paris was a resounduing success when tested, but a blanket speed limit reduction may also have been a contributing factor
Beijing managed a 40% reduction in pollution, but again subsidised the registration system by banning all HGVS, older vehicles and drivers who lived tside the city
There are some simple systems out there, and it was only 5 years ago that the Paris experiment proved successful, all it needs is litte determination and the guts to stand up to the motoring lobby