Enlarge Image Forrester

Replacing human drivers with computers will cut accident rates, but don't expect your insurance costs to go down anytime soon.

That's the assessment of Forrester Research analysts who surveyed auto industry players about the disruptions coming from self-driving cars. A reduction in the 94 percent of accidents caused by human error sounds great, but self-driving cars still won't be perfect, and it'll be hard to figure out whether sensors, networks, software or something else is to blame.

"Insurance claims will require more detailed investigations into the cause of accidents, which, along with the cost of repairing more expensive vehicles, will keep costs high," Forrester said in the report, published Thursday.

Also, a machine packed with electronics will need more than a wrench and some touch-up paint to fix.

"Insurance premiums [will] stagnate for years before meaningful declines," Forrester said. "Even the best-case cost of $7,500 for Waymo's forthcoming Lidar sensor is still a big chunk to add to the cost of a car," the firm said about the self-driving car technology subsidiary from Google parent Alphabet.