The Kaefer is the best selling unchanged single design ...
Corolla/Auris is a nameplate used for several different cars they even switched the basic layout from RWD to FWD in the 10 generations. In some nations they even sold other Toyota cars under the name Corolla..example in Germany the Tercel was sold as Corolla. They throw Coupe, limo, hatchback, minivan.. every single version based on the Corolla into their counting...
VW counts Golf (30million) WITHOUT the sedan, van or coupe versions of the Golf
Jetta/Bora (10million by 2011)
Gol (7million by 2012 sold in south america)
Scirocco (~2million by 2012)
Eos, Touran(minivan 1.13million by 2011), Lavida (China), Sagitar (Cina), Caddy (small transport version of the Golf)
if VW would like Toyota throw in all cars based on the Golf in the counting they would blow the Corolla out of the water by miles.