A strictly linear evolution of the cosmological expansion scale factor is a
characteristic feature in several classes of alternative gravity theories
as also in the standard (Big-bang) model with specially chosen equations of
state of matter. Such an evolution has no free parameters as far as the cl
assical cosmological tests are concerned and should therefore be easily fal
sifiable. In this Letter we demonstrate how such models present very good f
its to the current supernovae Ia data. We discuss the overall viability of
such models. (C) 2001 Published by Elsevier Science B.V.