\documentclass[oldtable,color]{../../../fithesis3}
\usepackage{tabularx}
\thesissetup{basePath=../../.., faculty=ped}
\begin{document}
  \begin{tabular}{ccc}
    a&b&c\\
    d&e&f
  \end{tabular}
  \begin{tabularx}{\textwidth}{ccc}
    a&b&c\\
    d&e&f
  \end{tabularx}
\end{document}
