Does section 831.2 immunity apply to a motor vehicle accident in a public park?

In Rendak v. State of California (1971) 18 Cal.App.3d 286, 95 Cal.Rptr. 665, the judgment entered following the granting of a nonsuit was affirmed based on section 831.2 immunity. The plaintiffs' decedent was killed when a portion of a cliff slipped into the ocean at Brighton Beach Park in Santa Cruz County. The plaintiffs argued that the existence of improvements in the public park negated the immunity provided by section 831.2. In rejecting this argument, the court held that "improvement of a portion of a park does not remove the immunity from the unimproved areas." (Id., at p. 288, 95 Cal.Rptr. 665.)