Oh, and you don't HAVE to drive them, there are 2 RT buses every weekday from Seaview into Hilo (many more from Pahoa)... Link to the bus schedules:
http://heleonbus.org/
You can make a 1/2 day or day trip on the bus! Even better, the buses to Keaukaha leave the PKP mall every hour from 7:45 - 10:45, then from 1:38 until 4:38 - it takes 18 mins to get to Richardsons from the mall, then you can go from Richardsons to the downtown bus terminal, by way of the scenic Banyan drive in 17 min, every hour from 7:03 - 11:03 then from 1:38 til 4:38. The bus terminal is right across from the Hilo Market, so on a market day you can have a grand tour of Hilo!
So take the 9:05 from Seaview, make it to the mall around 10:30 - take the 10:45 to one of the "string of Pearls" parks.... then return from the park to the downtown bus terminal (possibly stopping on Banyan to walk over to Coconut island & back for an hour or 2) shop downtown, return to Seaview on the 5:05 Pahoa bus & get back to Seaview at 7:10
ETA:the Saturday bus leaves town at 4:00 gets to Seaview at 5:45
All of these rides, no $$$$! one of the best deals around!