Remove whitespace between columns in table

I'm trying to create a table using booktabs, but for some reason I get extra whitespace between my last two columns.

\documentclass{article}

\usepackage{booktabs}
\begin{document}

\begin{table}\centering
\begin{tabular}{@{} c c c @{}} \toprule
\multicolumn{3}{c}{coordinates space filler}\\
\cmidrule{1-3}
x & y & z \\
\midrule
a & 0 & 0  \\
b & 0 & 0  \\
c & 0 & 0  \\
\bottomrule
\end{tabular}
\end{table}
\end{document}


And this produces a large white space between the y-column and the z-column. The larger I make the 'coordinates space filler' the worse it becomes. But the distance between my x and y column is always okay.

Your tabular without the coordinates space filler is not wide enough. I suggest using a fixed-width column for all columns to stretch things out far enough:

\documentclass{article}

\usepackage{booktabs}
\usepackage{array}
\newcolumntype{C}{>{\centering\arraybackslash}p{3em}}
\begin{document}

\begin{tabular}{@{} C C C @{}}
\toprule
\multicolumn{3}{c}{coordinates space filler} \\
\cmidrule{1-3}
x & y & z \\
\midrule
a & 0 & 0  \\
b & 0 & 0  \\
c & 0 & 0  \\
\bottomrule
\end{tabular}
\end{document}


If a spanning cell is wider than the columns it spans all the extra space goes into the last column.

You can hide the width with

\multicolumn{3}{c}{\makebox[0pt]{coordinates space filler}}\\