2011 Scion FR-S
Toyota was using the Scion brand to attract younger customers. The company had been doing great with small and affordable cars when it decided to make a sports car. The FR-S was a big hit at car shows. Scion must have assumed that this would mean good sales in practice. When it was released to the general public, it fizzled out. There was nothing wrong with it, but it seems like consumers did not like it all that much.
2013 Subaru Impreza WRX
Subaru redesigned the Impreza WRX in 2013. The small car was a staple in their lineup for almost 20 years, but execs thought it was getting stale. This new concept blew viewers away, but this was not recreated when it was finally released. The Impreza WRX was not that impressive or even different from the old iteration. Subaru might have thought they had a winner on their hands, but they were wrong.