Neptune also hit a solo home run later in the game.
Used Cars won three of the five meetings between the teams during the season, with three of the five outcomes being decided by one run.
Used Cars ended its season with a 10-4 record. Sandpiper finished 9-5-1.
Sandpiper 9, Used Cars 8
The Sandpiper win forced a winner-takes-all second game in the double-elimination tournament, which Used Cars won, 12-8.
In this game, Ryan Neptune's solo home run in the top of the seventh tied the score at 8 and Jimmy Whalen's RBI single in the eighth won it for Sandpiper.
Sean Bill had a three-run home run in the first inning and singled, and Neptune singled twice and walked in three other plate appearances.
Sandpiper had built a 7-2 lead but Used Cars rallied with a six-run sixth inning to take an 8-7 lead. The highlight of the inning was a grand slam by Nathan Paerels and a solo homer by pitcher Dave McCollum.
Hennessey's 7, Mesa Verde Partners 2
Hennessey's replaced Mesa Verde Partners as league champion by winning the division final.
Dave McCollum shined on the mound for Hennessey's, giving up just one hit, a two-run home run to Jeff Greenough in the sixth inning. McCollum faced just three batters over the minimum 21 batters.
Ryan Neptune had a solo home run for Hennessey's.
Phil McManus managed a five-hitter, but the Mesa Verde Partners defense was guilty of three errors in the fifth inning, which led to five of Hennessey's runs.
Mesa Verde Partners 12, Hennessey's 9
In a game prior to the league final, Danny Lane and Matt Kucero hit home runs and Jeff Pich and Bill Toon each had RBIs during a four-run second inning that propelled Mesa Verde Partners to the win.