Cars from maruti suzuki india.

The transmission, the weight and the aerodynamics of the vehicle all have an impact on the milage.

Practically Zen is mileage is better.

Theoritically also it is better.

It has aerodynamic technology which Honda uses. & get beetter inside space & less outside space so it is more smarter in traffic .

So Zen Estilo is best in mileage

Milage depends of various factors like kind of road, speed, traffic.
l think zen has more milage than wagonr because it has less weight, more compact, less electrical load on the engine.
It also depends upon the variant whether Lxi or Vxi because of different features.
Some cars due to fault in engine or blockage may also increase fuel consumption.
Tyre pressure also should be correct or else less milage.
Hope this helped.