According to Official Guinness Records,
The largest parade of Karwa buses consisted of 325 buses and was organized by Mowasalat - Transport Company in Doha, Qatar, on 21 August 2009.
A 4.8 km-long convoy of 325 Karwa buses travelled a stretch of 5 km on the Shahaniya-Dukhan highway, which is about 56 km from Doha.
For a complete list of 2009 records, please visit 2009 Guinness Records in Qatar.