  For every prime $p$, Mohan Kumar constructed examples of stably free modules
of rank $p$ on suitable $(p+1)$-dimensional smooth affine varieties. This note
discusses how to detect the corresponding unimodular rows in motivic
cohomology. Using the recent developments in the $\mathbb{A}^1$-obstruction
classification of vector bundles, this provides an alternative proof of
non-triviality of Mohan Kumar's stably free modules. The reinterpretation of
Mohan Kumar's examples also allows to produce interesting examples of stably
trivial torsors for other algebraic groups.
