The National Highway Traffic Safety Administration is best known for rating and monitoring vehicle safety, but also keeps a database of customer complaints about all types of car problems.
For the 2013 model year, the Nissan Altima has about 4-10 times as many complaints of powertrain problems, when compared with several of its direct competitors (as of March 2018).
Is it possible the number of complaints is higher just because there are more Altimas on the road? According to sales figures from goodcarbadcar.com, no -- the Altima sold fewer units in the U.S. than the Camry or Accord, and only slightly more than the Fusion, Malibu, or Sonata.
If we calculate the number of NHTSA powertrain complaints per 100,000 vehicles sold for all six of these mid-size sedans, the Altima sticks out like a sore thumb:
For the Altima, the rate of powertrain complaints is anywhere from 3.5-9 times higher than any of its five competitors in this sample.
Keep in mind that the NHTSA is a government agency with no financial incentive to favor one make or model over another. Is it possible that something about the NHTSA complaint database systematically favors more complaints from Nissan owners? If anyone has reason to believe this, feel free to let us know.
CarComplaints.com is a private website, but serves as a forum for vehicle owners to submit reports of problems to help build a database.
As of March 2018, the 2013 and 2014 Altima both make the top 10 "worst vehicles" list on CarComplaints.com. This list takes into account both the number of complaints and their severity.
This site's database includes dozens of makes, hundreds of models, and most model years back to 1999-2000. So less than 3% of all model years tracked on CarComplaints earn the dubious honor of cracking the top 10 worst vehicles.
One way to interpret this is that 2013-2014 Nissan Altimas have received more complaints about serious issues, 4-5 years into their lifespan, than many lower-cost models from manufacturers like Kia and Hyundai have received 10-15 years into theirs.