Catalin,

Yes, you can put manual hubs on the front of a VehiCross. I have them on mine. It's a very simple modification. Unfortunately it makes very little difference on fuel consumption. I only have them on mine so that I can tow it behind my RV.

With very careful use of the skinny pedal, you MAY be able to get close to 20mpg but there's no way to get any better with the stock setup.

If you have wrenching skills, converting a VehiCross to a diesel engine would be a very nice option for you. I do not recall anyone attempting it yet though so you'd have to figure it all out as you go.

Tom