Someone mentioned the Panoz Esperante (GTLM) above... this is the thing. Not really oddball to me, it sounded great, and was actually competitive in the ALMS and at Le Mans I believe. Lasted a long time in the ALMS too (six? seven? seasons).
Panoz Esperante GTLM - Dominik Farnbacher by
Richard Wintle, on Flickr
And then someone else mentioned the Abruzzi... gaaaaah my eyes!!!! And boy was it ever (a) slow, and (b) unreliable. Only made a few ALMS starts, so I can consider myself honoured to be among those who actually saw it race.
Panoz Abruzzi, Mosport 2011 by
Richard Wintle, on Flickr
The thing looked like a vacuum cleaner from the front. Argh.
AAAAGH! It's coming for me! by
Richard Wintle, on Flickr
Some might say this was its finest hour...
Dead Panoz, live Ferrari. by
Richard Wintle, on Flickr