According with Wikipedia, "Touring car racing is an auto racing competition with heavily modified road-going cars". It also explains that "while not nearly as fast as Formula One, the similarity of the cars both to each other and to fans' own vehicles makes for entertaining, well-supported racing. The comparatively lesser effect of aerodynamics also means that following cars have a much easier time of passing than in F1, and the more substantial bodies of the cars makes the occasional nudging for overtaking much more acceptable as part of racing."
This is basically what you need to know about touring car races: few laps, drivers with big balls, and a lot, a lot, a lot of nudging.
There are a lot of different championships all over the world, national and international. The most famous ones are the WTCC (World Touring Car Championship), the TCR International Series, which both run all over the world, and then some national championships such as the german DTM (Deutsche Tourenwagen Meisterschaft), the BTCC (British Touring Car Championship), and the australian Supercars Championship. Less known championships are the Scandinavian Touring Car Championship, the german VLN that is setted in a lot of race in the green hell called Nürburgring, and the brand new italian CIT (Campionato Italiano Turismo). Obviously in almost every part of the world there are other national championships, and you can be sure to find great fightings in all of them!
Regulations are different between the championships, but new TCR cars (2wd, 2liters turbo, about 330hp) are the most diffused. DTM cars are the most extreme, more similar to prototype cars, the derivation from series cars is less evident.
In this tribe, you will see a lot of stuff about history of touring cars, news from the current championships, and all the most rare models that raced in these fantastic events!
So just stay tuned!