Yup. Good old fashioned axle grease.
Insurance companies’ and auto accident attorneys will be all over Google. Can you imagine the settlements plaintiffs will get when one of the Google vehicles malfunctions and causes a 20 car pileup complete with Mack trucks and decapitations? If you want to bankrupt a company go right ahead though I have a sneaking suspicion that Google’s intent was to market this to trucking companies so they wouldn’t have to pay salaries. I bet they were already projecting profits on this endeavor.