i cannot remember if this is an old issue but in 0.53 stable the fast and slow forward (Q/E) although properly mapped in the key bindings do nothing in the v3s. only normal forward (W) makes the car move. holding down turbo (SHIFT) does give more power.

under normal forward (W) + turbo the v3s does go well in the plains but struggles badly when faced with a hill, slowing down to below walking pace. giving it a bit of a run up to get some speed helps. hill starts are virtually impossible.