By no means a specialty of mine but in The Pursuit of Glory, Tim Blanning notes that a journey by road (i.e. average horse or carriage pace) from Paris to Toulouse in 1650 took two weeks. In 1782 the roads had improved enough that that figure was cut in half.

He doesn't specially mention Marseilles, but he says that to go from Paris to Lyon in 1664 took 10 or 11 days, so it seems plausible to me that the figure for Marseilles would be similar to Toulouse.

He basically makes the point that road management in the late 17th century in France was in a bit of a shambles and didn't improve substantially until the 1740s.