Is filing bankruptcy an event of default which could lead to a car repossession?

If you purchased your car (not if you leased it), and California law applies, the answer now is no. Simply filing for bankruptcy or being a debtor in bankruptcy can no longer be deemed an event of default under a purchase contract or car loan. The California Legislature has added provisions to California Civil Code § 2983.3 (which applies to purchases with dealer-assisted financing) and California Financial Code § 22329 (which applies to loans secured by vehicles), effective as of January 1, 2023, stating that neither the act of filing a petition commencing a case for bankruptcy by any person liable on the contract nor the status of any of those persons as a debtor in bankruptcy constitutes a default under the contract, and neither may be used as a basis for accelerating the balance due under the contract or for repossessing the motor vehicle.