Feb 17 (Reuters) - Volkswagen Ag
* Says voluntarily issues workshop recall for natural gas models up to and including model year 2014 as a precautionary measure
* Says voluntary recall affects passat, touran and caddy natural gas models
* Says in germany a total of 6,270 cars (2,359 caddy, 2,361 touran and 1,550 passat) are affected by this recall Further company coverage: (Frankfurt newsroom)