At the moment, California courts haven't yet made up their minds about the answer to this question.
Proposition 47, passed by California voters in 2014, provided that theft of property worth less than nine hundred fifty dollars ($950) would be a California misdemeanor for most defendants. (Prior to Prop 47's passage, all theft of motor vehicles, regardless of their value, was considered to be grand theft auto, which potentially carries felony penalties.)
The problem is that Prop 47 didn't say anything Vehicle Code 10851, California's joyriding law. Joyriding is the crime of taking and driving someone else's car even if you don't intend to keep it. (In contrast, normal grand theft auto under California's grand theft law requires that the defendant intended to deprive the owner of the car permanently or for a material period of time.) Before Prop 47, joyriding was a wobbler, which is a crime that can be charged as either a misdemeanor or a felony.
Prop 47 makes it clear that stealing a car worth less than $950 is a misdemeanor. But it is NOT clear that the same is true of taking a car worth less than $950 for a joyride.
One California court recently said that Prop 47 DOES apply to joyriding. In People v. Gomez, the California Court of Appeals for the Fourth Appellate District said that under Prop 47 a VC 10851 conviction involving a car worth less than $950 should be a misdemeanor.
By extension, this means that if you were convicted of joyriding as a felony and the car involved was worth less than $950, you should be able to apply to have that conviction reduced to a misdemeanor under Prop 47.
The problem is that the same California Court of Appeals had said exactly the opposite a few months earlier. In People v. Page, the court concluded that--because the statutes added to the Penal Code by Prop 47 don't mention Vehicle Code 10851--joyriding remains a wobbler regardless of the value of the car involved.
The confused state of the law on this point means clients with felony convictions for joyriding in an inexpensive car should still try for a Prop 47 petition for resentencing.