  We consider hypoelliptic equations of kinetic Fokker-Planck type, also known
as Kolmogorov or ultraparabolic equations, with rough coefficients in the
drift-diffusion operator. We give novel short quantitative proofs of the De
Giorgi intermediate-value Lemma as well as weak Harnack and Harnack
inequalities. This implies H{\"o}lder continuity with quantitative estimates.
The paper is self-contained.
