The "lighter load = less wear" argument makes sense.
But if we're just going on anecdotal owner complaints (eg. on forums), the apparent difference could be a sampling issue.
Nissan has sold FAR more CVT's than Mitsubishi, so even if the failure rate were the same, it'd be easy to get the mistaken impression that there are more Nissan CVT problems than Mitsu CVT problems.
Look at Versa (uses the CVT7) sales vs. Mirage in the U.S.
2014 ... 139,781 vs. 16708
2015 ... 144,528 vs. 21515
2016 ... 132,214 vs. 22226
2017 ... 106,772 vs. 22386
2018 ... 75,809 vs. 24316
2019 ... 66,596 vs. 26966
Totals ... 665,700 vs. 134,117
The only way we can know for sure is if the companies release stats on warranty work/replacements.
Anybody want to ask them? I have one guess what they'll say.
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View my fuel log 2014 Mirage ES 1.2 manual: 62.4 mpg (US) ... 26.5 km/L ... 3.8 L/100 km ... 74.9 mpg (Imp)