A vehicle comprises a chassis, a pair of driving wheels, a pair of idle wheels, at least one steering group, and a differential. The steering group is capable of positioning one of the pairs of wheels in a steering geometry where an axis of each of the wheels of the pair of wheels capable of being positioned by the steering group intersects with the remaining axis within a ground-support quadrilateral formed by the pairs of wheels. The differential comprises an outer case, an inner case, a selective engagement, a selective blocking means, and a selective direct gearing means. When the inner case is coupled to the outer case a first half-shaft and a second half-shaft are driven similarly and when the inner case is coupled to the chassis and one of the half-shafts is drivingly engaged with a crown gear the first half-shaft and the second half-shaft are driven opposingly.