  Currently there is a variety of scalar field models to explain the late time
acceleration of the Universe. This includes the standard canonical and
non-canonical scalar field models together with recently proposed Galileon
scalar field models. One can divide all these scalar field models into two
broad categories, namely the thawing and the tracker class. In this work we
investigate the evidence for these models with the presently available
observational data using the Bayesian approach. We use the Generalized
Chaplygin Gas (GCG) parametrization for dark energy equation of state (EoS) as
it gives rise to both the thawing and tracking behaviours for different values
of the parameters. Analysis of the observational data does not give any clear
evidence for either thawing or tracking behaviour within the context of
background cosmology, However, if we consider the evolution of inhomogenities
and analyze the data in this context then there is a significant evidence in
favour of thawing behaviour.
