San Francisco has some of the slowest, most prone to break down public transit when compared to 16 "peer cities," according to a report sanctioned by the city.

San Francisco recently released a new "transportation benchmarking" tab on its Performance Scorecards website, spotted Thursday by Curbed SF.

The site pitted the city's transit failures and successes against a handful of metropolitan areas contending with similar transportation obstacles. These cities include: Baltimore, Boston, Chicago, Denver, Los Angeles, Long Beach, Miami, Minneapolis, Oakland, Philadelphia, Portland, Sacramento, San Diego, Seattle and Washington D.C.

Muni buses traveled an average of 8.1 mph in 2016, compared to the peer average of 10.6 mph. The city light rail system fared worse — it averaged five mph slower than its peers.

"For every mode, San Francisco ranks last or second to last in average speed," the report says. Bus speed is affected by "density, congestion and usage," and has been declining over time.

San Francisco transit is also disposed to failure. Muni, light rail and trolleybuses in the city were taken out of service after 7,000, 5,000 and 4,000 miles in-service on average, placing SF at the bottom of its peer group for most problem-prone transportation.

The San Francisco Municipal Transit Agency has promised to replace all Muni vehicles with new electric buses by 2035.

With the bad news comes some good: San Franciscans opted to take public transit far more often than their city-dwelling peers. According to the report, 34 percent of San Franciscans use public transportation, compared to the peer average of 17 percent.

San Francisco residents also drive less than those in other cities. Sixty percent of commuting is done without car in San Francisco, the report says, compared to 33 percent in peer metros.

Michelle Robertson is an SFGATE staff writer. Email her at mrobertson@sfchronicle.com or find her on Twitter at @mrobertsonsf.