  We explore the dynamics of dark energy models based on a Dirac-Born-Infeld
(DBI) tachyonic action, studying a range of potentials. We numerically
investigate the existence of tracking behaviour and determine the present-day
value of the equation of state parameter and its running, which are compared
with observational bounds. We find that tachyon models have quite similar
phenomenology to canonical quintessence models. While some potentials can be
selected amongst many possibilities and fine-tuned to give viable scenarios,
there is no apparent advantage in choosing a DBI scalar field instead of a
Klein-Gordon one.
