The most unreliable vehicle I've ever owned is my 2007 Acura MDX - constant electrical problems causing no-start (and not just from a dead battery). Then at only 170,000 kms, the motor had to be replaced (burning oil in 2 cylinders, one of which had zero compression).
Compared to my "unreliable" bikes:
2002 Ducati 998:
25,000 kms - TPS sensor failed
29,000 kms - timing belts shredded and valves bent (improperly installed by inexperienced dealership tech)
45,000 kms - plastic fuel line quick release started leaking from threads
60,000 kms - cracked plastic coolant expansion tank (might have been pressure cap failing to vent)
65,000 kms - starter sprag clutch failed (my fault for using undersized lithium batteries in near freezing weather)
2015 Ducati Hyperstrada:
20,000 kms - erratic throttle response and limp mode (turned out to be loose battery terminals, but because I was paranoid about the supposed throttle, O2 sensor, ECU, etc. issues I "read about on the internet", I never though to check anything simple).
2007 Aprilia SXV:
None so far at 14,000 km's and counting - no sealant issues, starting problems, or grenading. Just did 500 km's on it a few days ago to Southwood and Big Chute.