The maximum speed \( v_{{max}} \) in a circular motion, where friction provides the centripetal force, is given by:
\[
v_{{max}} = \sqrt{R \cdot g \cdot \mu}
\]
where:
- \( R = 50 \, {m} \) is the radius of the curve,
- \( g = 9.8 \, {m/s}^2 \) is the acceleration due to gravity,
- \( \mu = 0.34 \) is the coefficient of friction.
Substitute the given values into the formula:
\[
v_{{max}} = \sqrt{50 \times 9.8 \times 0.34}
\]
\[
v_{{max}} = \sqrt{166.6} \approx 12.91 \, {m/s}
\]
Thus, the approximate maximum speed of the car is \( 13 \, {m/s} \).