They could easily change the last item "(e)" in this description https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=500.
500. “Recreational off-highway vehicle” means a motor vehicle meeting all of the following criteria:
(a) Designed by the manufacturer for operation primarily off of the highway.
(b) Has a steering wheel for steering control.
(c) Has nonstraddle seating provided by the manufacturer for the operator and all passengers.
(d) (1) Has a maximum speed capability of greater than 30 miles per hour.
(2) A vehicle designed by the manufacturer with a maximum speed capability of 30 miles per hour or less but is modified so that it has a maximum speed capability of greater than 30 miles per hour satisfies the criteria set forth in this subdivision.
(e) Has an engine displacement equal to or less than 1,000cc (61 ci).
(Added by Stats. 2012, Ch. 165, Sec. 1. (AB 1595) Effective January 1, 2013.)
ROHV = https://leginfo.legislature.ca.gov/faces/codes_displayText.xhtml?lawCode=VEH&division=16.5.&title=&part=&chapter=8.&article=
VEHICLE CODE - VEH
DIVISION 16.5. OFF-HIGHWAY VEHICLES [38000 - 38604]
( Division 16.5 added by Stats. 1971, Ch. 1816. )
CHAPTER 8. Recreational Off-Highway Vehicles [38600 - 38604]
( Chapter 8 added by Stats. 2012, Ch. 165, Sec. 3. )
38601. A person shall not operate, or allow a passenger in, a recreational off-highway vehicle on public lands, as described in Section 38001, unless the person and the passenger are wearing safety helmets meeting the requirements established for motorcycles and motorized bicycles pursuant to Section 27802.
(Amended by Stats. 2019, Ch. 469, Sec. 13. (SB 785) Effective January 1, 2020.)
It's not an ATV https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=111.
It's not a Golf Cart 😆 https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=345.
It's not a Low Speed Vehicle https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=385.5. Lots of people get there UTVs registered this way with a legal CA road plate.
It could be a Utility-Terrain Vehicle aka "UTV" https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=531.
It's not a Specially Constructed Vehicle "SPCN" https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=580.
So with all that it depend on either UTV Section #531 or ROHV #500 as the defining factor till #500 is changed... Expect a LEO to know any of this is laughable, even if they are an OHV enthusiast.