Automakers, tech companies, and startups are often quick to share where they stand in that race. But without the data it’s impossible to vet those claims or accurately evaluate which company has the most robust autonomous vehicle technology.

The California Department of Motor Vehicles released a series of reports Wednesday from 11 automakers and tech companies that gave the public a peek at their development of self-driving car technology.

Any company issued a testing permit from the California DMV must submit an annual report detailing its so-called “disengagements,” a jargon term that means the number of times drivers have had to take control of a car because the software failed or for safety reasons. For example, a driver might take control if it encounters another car traveling the wrong way down the road or a pedestrian or cyclist acts erratically.

These annual reports, which the DMV released Wednesday, provide some insight into where automakers and tech companies stand in the race to develop autonomous vehicles. It’s not the only measure, however. Companies are testing self-driving vehicle technology on public roads, research centers, and their own testing facilities other states. But for the companies that did submit reports, it does provide a hint of where they stand and what they’re up to.

Waymo (Google) is leading

It takes only the quickest of glances at the reports filed with the California DMV to see that Waymo, the Google self-driving car project that spun out to become its own company, is way ahead in terms of total miles tested on public roads in California.

The numbers are striking—and show that the company has improved its self-driving software.

Waymo vehicles drove nearly 636,000 miles on public roads in 2016, a 49% increase from the previous year. And yet, the number of “disengagements” fell nearly 64% from 341 in 2015 to 124 last year.

In all, the total rate of disengagements per 1,000 miles driven fell from 0.80 to 0.20 over that one year time period, according to the report. It’s also notable that Waymo tests in more complex urban and suburban environments, and not highways where there are fewer variables such as children, cyclists, and traffic infrastructure.

“We’ve been able to make dramatic improvements to our technology because we use each of these disengages to teach and refine our car (that’s why we set our thresholds for disengages conservatively), Dmitri Dolgov, head of self-driving tech at Waymo, wrote in a post on Medium. “For each event we can create hundreds — and sometimes thousands — of related scenarios in simulation, varying the parameters such as the position and speed of other road users in the area.”

GM is quickly accelerating

This report is a study in how a big company (and capital and resources that come with it) can catapult a startup forward. Cruise Automation is a San Francisco-based developer of autonomous vehicle technology. And up until it was acquired by General Motors in March 2016 for more than $1 billion, the startup was testing its technology using a few Nissan Leaf vehicles.

The numbers tell the story. In January 2016, Cruise was testing three Nissan Leafs. That number topped out at five in April. A month later, the Nissan Leafs—with names like Scarlet and Quicksilver—began to drop off and 2017 Chevrolet Bolt EVs come onto the testing circuit.

By August, the Nissan Leafs were gone and Cruise had at least nine Chevy Bolts—with names like Pronghorn, Lynx, Platypus, and Cheetah—actively testing. By November, the company had 20 licensed vehicles in its testing lineup, according to the report filed with the California DMV.

Tesla has made it official

Tesla’s semi-autonomous driving system Autopilot, which rolled out in October 2015, has made it a leader in advanced driver assistance. Autopilot, a combination of sensors and software, is capable of parallel parking, steering and lane changing on highways. The semi-autonomous system has continued to improve, pushing it ahead of other automakers.

And yet, until 2016 the company wasn’t testing self-driving vehicle technology on public roads in California. That has changed. The automaker and energy company started testing four self-driving cars on California’s public roads in 2016, according to its disengagement report filed with the California DMV.

Some automakers didn’t do any—or very little—testing in California

There are 21 companies—from Volkswagen and Tesla to startups like Zoox and Drive.ai—that have been issued permits to test self-driving vehicles on public roads. Only 11 filed reports, and some of those reports simply acknowledged that they did not test any vehicles on public roads.

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Volkswagen Group of America, which includes luxury brand Audi, didn’t do any public testing in California. Honda didn’t either. Honda says it currently tests on a closed circuit, non-public course in Contra Costa County in California. BMW had just one vehicle testing in the U.S.

Other tallies of companies testing on public roads in California:

• Bosch: three autonomous vehicles
• Delphi: two autonomous vehicles
• Ford: two autonomous vehicles
• Mercedes: one autonomous vehicle
• Nissan: five autonomous vehicles

These low numbers don’t necessarily reflect the level of testing by a particular company. Automakers, tech companies, and suppliers are testing in a variety of other states and on closed courses.ur overall For instance, Ford’s overall fleet grew from 10 to 30 vehicles in 2016, although the build was not complete until December, according to a spokesperson. Those vehicles are used for a variety of engineering work, not just on-road testing and are spread throughout locations in Arizona, California, and Michigan.

It should be noted, that California has been focal point in the past for autonomous vehicle development. The low numbers could mean companies are pulling back from California and choosing to test in states with more permissive rules or closer to an automaker’s base of operations.

The big question is what are the other 10 companies that didn’t file reports up to?

These reports are wildly inconsistent

There is no standard, which means the disengagement reports vary from two pages to more than 34 from Waymo.

Some companies dig into the details, providing the location and specifics of a disengagement. Others simply state total mileage, the number of disengagements, and a brief one or two sentence explanation.

The upshot? It’s difficult to provide an accurate assessment of where these companies are in the race to develop autonomous vehicle technology because of this variability.