HPD stands for Honda Performance Development. The two ARX-03b cars in this shot use a turbocharged V6 engine for the LMP2 category.
For more information on the HPD program [link]
The #551 Siemens/ Alpina Watches/ Ohiya Casino Resort, HPD ARX-03b finished first in class and third overall. The #01 Tequila Patrón car finished third in class and sixteenth overall. There were some fast GT class cars in the field that day.
Le Mans Series presented by Tequila Patrón
Mazda Raceway Laguna Seca, Monterey, California