This data was for the three US states of Arizona, California and Pennsylvania.
The distance a car could travel before needing human intervention at the end of January was 0.9 miles, according to a report at Recode based on leaked Uber documents.
Uber uses different metrics to measure progress. One is the average distance a car can travel before a human has to take over for any reason; two is the distance between "critical interventions" (to avoid harm or hitting passers-by, for example), and three is the distance between "bad experiences" which cause discomfort like sudden braking.
However, the time between critical interventions has increased to about 200 miles in the seven days to 8 March. But progress does not seem to be steady, even though the previous week saw critical interventions every 114 miles.
At the end of January, that distance was 125 miles but it fell to 50 miles in the first week of February. The numbers increased over the next two weeks, before falling in the first week of March.
There were also more bad experiences in the week ending 8 March. In January, cars could go four miles without this type of experiences; this dropped to an average of two miles in the week ending 8 March.
A test in Arizona, on the Scottsdale Road, ended with the cars able to go only 0.67 miles between interventions and two miles between bad events.
The report said Uber had yet to make self-driving miles and engagements public while other competing companies in California had done so.