  We study the differential uniformity of the Wan-Lidl polynomials over finite
fields. A general upper bound, independent of the order of the field, is
established. Additional bounds are established in settings where one of the
parameters is restricted. In particular, we establish a class of permutation
polynomials which have differential uniformity at most 5 over fields of order
$3\bmod 4$, irrespective of the field size. Computational results are also
given.
