Maruti Ertiga CNG Review. The CNG Ertiga is now offered in VXi and ZXi variants. The top-end variant offering now adds a host of new features over the pervious model. There have been changes made under the hood as well with a new Dual VVT engine. We drove the Ertiga CNG in the streets of Delhi to test the performance and its features. Here are our impressions of the Maruti Ertiga CNG.