A building block system includes one or more building blocks and one or more wheels, each building block including a first elongate portion extending in a longitudinal direction, a second elongate portion extending in that longitudinal direction, an intermediate portion connecting the first elongate portion with the said second elongate portion at a middle position thereof, a first end portion extending in a transverse direction, perpendicular to that longitudinal direction, from the first elongate portion, at a side thereof opposite to the intermediate portion, and at a middle position thereof. A second end portion extends in that transverse direction, perpendicular to the longitudinal direction, from the second elongate portion, at a side opposite to the intermediate portion, and at a middle position thereof. It thus includes six protrusions and two voids, each void defined between an end of the first elongate portion and an end of the second elongate portion.

A toy vehicle includes a body, a first axle, a second axle, and a third axle connected to the body, and three pairs of wheels respectively coupled to the first axle, second axle, or third axle. The toy vehicle also includes a support configured to couple to an additional toy vehicle. Tilting the body of the toy vehicle to a first side causes the first axle to rotate in a first direction and the second and third axles to both rotate in a second direction, the second direction being opposite of the first direction.