Put simply, it is the science of running a car for next to nothing. The term 'Bangernomics' was the creation of motoring journalist and author James Ruppert, who in 1993 published a book of that title.
If you have no money, Bangernomics can be the lifeline that helps you get a better job, avoid having to live next door to work or depend on unreliable and expensive public transport. Even if you aren't that poor, following the Bangernomics philosophy will leave you with more money for the fun things in life - foreign holidays, smart clothes, single malt whisky, or whatever.
Or how about running a banger as daily transport, and using the money you save to buy an E-type Jaguar for the weekends, or a Harley-Davidson, or even a light aircraft?
That's how much money you are throwing away by doing what the motor manufacturers want you to do - buying a new car on finance, having it serviced by a main dealer (to keep up the warranty), then trading it in after three years for another new car.