We have updated results for the Sentra to include owner experiences through December 31, 2010. Other sources of car reliability information won't cover the months since last April until the summer or even fall of this year.
Repair frequencies, in terms of repair trips per 100 cars per year:
2008: 16, better than average
2007: 60, about average
2006: 16, no repairs reported, 11 cars
2005: 35, better than average
2004: 67, better than average
2002: 141, about average
2001: 61, better than average
Decent sample size for the 2008, small and even very small sample sizes for the others, which likely explains inconsistencies--additional participants very much needed.
A big thanks to AZhitman, this forum, and everyone who has been helping. We'll have further updates in May and August. With more participants, we could provide more precise information and cover all model years.
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Nissan Sentra reliability ratings and comparisons