The popularity of hybrid and all electric vehicles has increased in recent years, and comprise about 10% (world-wide, circa 2022) of new vehicles sold. There are three main types. Hybrid vehicles (HEVs) incorporate an internal combustion engine (ICE), an electric propulsion motor, a battery pack, and an electronic drive system including a generator, all integrated into one complete package. Their propulsion battery's size ranges between 5 and 35 kWh. Propulsion battery recharging is mainly done by the generator, and to a lessor degree using regenerative braking. Plug-in Hybrid Vehicles (PHEV) are similar to HEV, but the propulsion battery is much larger (≥50 kWh). They can also be recharged from the electrical grid.
All Electric Vehicles (EV) run on battery power alone. Their battery sizes are much larger, typically 120 kWh, but may be much larger. They must be recharged by the electrical grid, although all use regenerative braking as a means of extending their range.
The majority (≈93%) of these types of vehicles, use Li-ion battery technology, but other types are sometimes used (LiFePO4; lithium iron phosphate). Their interconnections are series/parallel designed to provide the voltage and current required. Voltages range from about 240 VDC to 780 VDC, with current capabilities as high as 3,000 amps! But unlike golf carts, their propulsion motors run on three-phase AC! Computer-controlled, solid-state circuitry is used to drive the motor(s), while in the mean time, generating prodigious amounts of harmonics, well into the VHF ranges. This fact makes using amateur radio in EVs, all but mutually exclusive!
The question remains, just how RF noisy are they? Although the level of RF emitted varies considerably from model to model, none of them are what amateurs would call quiet! All EVs use filtering to reduce the level of RFI emitted, however. And it should be noted, that HEVs, PHEVs, and EVs are exempt from Part 15 rules, specifically by Part 15.103 (a), so don't ask the FCC for help!
Seemingly every automobile manufacturer makes at least one model of EV. A few actually come close to meeting the aforementioned Part 15, with Ford Motor Company leading the way. However, operaing HF in any hybrid or electric vehicle, is a hit and miss situation.
Warranties on some EVs specifically prohibit the installation of amateur radio gear, but not in those exact words. Assuming there are no warranty issues, there are a lot of caveats. For example, coming in contact with the high voltage circuitry of propulsion batteries can be instantly lethal! Manufacturers do a wonderful job of isolating these circuits, but careless installation of amateur radio gear could place these dangerous circuits within reach! And, as noted in the wiring article, using so-called accessory sockets is also not recommended, due to their small feed wire size (≈14 to 16 AWG), and low current capability of just a few amps. And just because the fuse may be 15 amps, is no indication you can safely draw that level of current. The same issue applies to the USB ports too.
Here's an excerpt from the document National Fire Protection Association. While the NFPA is concerned with emergency response, potential mobile operators of these vehicles should also be concerned as well. You might want to read this article published on the Tesla Motors web site:
Electric propulsion systems introduce new and possibly unanticipated hazards to emergency responders, although these do not include anything that members of the fire service would consider particularly challenging. For example, EVs and HEVs utilize high voltage power used for propulsion in conjunction with their low voltage electrical systems used for accessory lighting. The cabling for these high voltage systems were voluntarily colored bright orange for easy and consistent identification. In certain recent models cabling has appeared that, although it does not carry high voltage, still presents an appreciable and dangerous shock hazard, and these are identified using blue and yellow to color-code cables. In the meantime, additional shock hazards exist in all vehicles from certain features of the low voltage electrical system, such as, for example, the use of special high intensity discharge headlights.
If you still pursue the installation of amateur radio into your EV, here is one more consideration which should be followed. Proper installation of antennas onto EVs, require permanent installations. In other words,not mag mounts! The reason is, that mag mount antennas are plagued with common mode issues, which essentially turn the feed line into part of the antenna. If enough RF is radiated, the drive-by-wire circuitry could be effected negatively. These include so-called automatic pilots, collision-avoidence, and braking subsystems. The possiblely dangerous results should be obvious.