Brief report:
Rented a small 4WD truck (a Chevrolet Vitara). Drove up to 3820 meters (12,533 ft). Couldn't drive any higher because of major mud on the dirt/muddy road. Started the Guagua Pichincha hike at 10:50am. Summited by 1:30pm. Talked to a Polish & a German guy at the summit. Left the summit at 1:45pm. Back at the truck at 2:58pm (~ 4 hrs roundtrip). Then, we drove to Aloasi, Machachi and stayed at Hosteria La Estacion.
Additional info about climbing Guagua Pichincha can be found here.