A mobile toy which is propelled by a flywheel is described. The mobile toy includes a body member having a set of protrusions which extend beyond the body member. An axle extending through the flywheel is positioned in the set of protrusions, such that each protrusion operates as an axle cap. Alternatively, a set of axle caps are formed at the end of the axle. The flywheel is formed as a displaceable flywheel which is repositionable or removable from the body member. The flywheel may be adjusted within the mobile toy at multiple positions relative to the mobile toy for use of the mobile toy on multiple types of surfaces and for various play configurations. A set of detachably attachable extension elements attached with the axle caps alter the appearance as well as the play capabilities of the mobile toy.