  The robust field-insensitive heavy fermion features in Sm$_3$Ru$_4$Ge$_{13}$
and the magnetic phase transition at $T_N \approx$ 5~K are studied using
magnetization $M(T)$, specific heat $C_p(T)$, resistivity $\rho(T)$ and thermal
conductivity $\kappa_T(T)$. The average crystal structure of
Sm$_3$Ru$_4$Ge$_{13}$ conforms to the cubic space group $Pm\bar{3}n$ however,
signatures of subtle structural distortions are obtained from the x ray data.
The magnetic susceptibility, $\chi(T)$, follows a modified Curie-Weiss law
indicating the presence of crystal fields of Sm$^{3+}$ and the significance of
van Vleck terms. No sign of ferromagnetism is observed in $M(H)$ of
Sm$_3$Ru$_4$Ge$_{13}$ which yields only 0.025~$\mu_\mathrm{B}$/f.u.-Sm at 2~K,
7~T. The Sommerfeld coefficient, $\gamma \approx$ 220~mJ/mol-Sm K$^2$,
estimated from the analysis of low temperature specific heat suggests the
formation of heavy quasi particles at low temperature. Though a ln$T$
dependence of $\rho(T)$ is observed till 60~K, the resistivity behavior is
accounted for by assuming a two-band model for activated behavior of charge
carriers. The field scans of resistivity, $\rho(H)$, below $T_N$ display
significant nonlinearity while those above the $T_N$ are more metal-like. Low
values of thermal conductivity, $\kappa_T(T)$, are observed in
Sm$_3$Ru$_4$Ge$_{13}$ however, displaying an anomaly at $T_N$ which signifies
magnetoelastic coupling. A fairly high value of Seebeck coefficient, $S
\approx$ 40~$\mu$V/K is observed at 300~K. We identify Sm$_3$Ru$_4$Ge$_{13}$ as
a low charge carrier density system with unusual field-insensitive heavy
fermion features very similar to the filled skutterudites.
