What is the test for a jury to find grossly negligent vehicular manslaughter?

A number of cases have addressed grossly negligent vehicular manslaughter. In People v. Leitgeb (1947) 77 Cal.App.2d 764, 769, [cited with approval in People v. Bennett, supra, 54 Cal.3d at p. 1039], in which the jury found gross negligence: "[D]efendant was driving his car at 40 miles an hour, veered across a corner of, and struck decedent in, the safety zone. According to his own testimony, he did not see decedent until the instant he struck him. There was no evidence whatever as to any circumstance that would have made it necessary for defendant to invade the safety zone, nor was there any evidence of any obstruction in the street, or other condition which would have prevented defendant's seeing decedent standing in the safety zone. The corner was sufficiently lighted for other witnesses to see objects in the street."