I realise this about 6 months after the initial query, but thought I would add my interpretation anyway.
An extract from Jedko 2nd edition rules states that:
....Axis units can move 4 (or 20 road) hexes by strategic movement without using fuel.....
From this, as strategic movement is double that of ordinary movement, you could assume that Axis units can move 10 hexes by road without using fuel. This is the way I have read and applied the rule in the past.
On the other hand my 2nd edition Jedko (bookcase) rules state:
'Every time an Axis unit moves more than 2 hexes (or 4 hexes strategically) the fuel index is reduced by 1. If there is no fuel available no Axis unit may exceed 2 hexes or 4 hexes strategically during movement. Fuel is not required for replacement units or the Rommel unit.'