The best
way is from Autostrada 75bis, which runs across the top of Lago
Trasimeno, connecting the A1 Autostrada with Perugia.
On 75bis
coming from West (the A1), take the Cortona Exit to the South and
then take the road to the East when you see the Pozzuolo / Petrignano
sign.
On 75bis coming from
the East (Perugia), take
the Castiglione del Lago exit, then take the first exit West
(under the railroad tracks) and follow signs to Petrignano.