As I watch the lead-up to the American Solar Challenge next July, the chart above (click to zoom) shows the teams currently registered, with my estimate of current construction progress (based on a combination of social media reports and official paperwork). Team colours in the chart are my best guess in some cases. The University of Minnesota (Team 35) is in the lead (with an existing car and with most of the race paperwork done). Among teams building new cars, Italian team Onda Solare (559) and Canadian team Poly Montreal (55) lead the pack.
My ASC race information page will be updated from time to time with information on the progress of these and all the other teams. It also decodes the team numbers.
Render of Esteban9, the solar car being built by Polytechnique Montréal (picture credit)