\begin{table}
\centering
\begin{tblr}[         %% tabularray outer open
]                     %% tabularray outer close
{                     %% tabularray inner open
colspec={Q[]Q[]Q[]},
hline{2}={1-3}{solid, black, 0.05em},
hline{1}={1-3}{solid, black, 0.08em},
hline{8}={1-3}{solid, black, 0.08em},
cell{2,4,6}{1}={r=2}{valign=h},
}                     %% tabularray inner close
cyl & am & mpg \\
4 & 0 & 23 \\
4 & 1 & 28 \\
6 & 0 & 19 \\
6 & 1 & 21 \\
8 & 0 & 15 \\
8 & 1 & 15 \\
\end{tblr}
\end{table} 
