No, they're not exempt but they benefit from the lowest level of company car tax. Currently Benefit in Kind is 2% from April 2022 until April 2025 after which company car tax rates on EVs will increase from April 2025 by 1% pa for 3 years. The rates will be 2% to 2024/25, 3% for 2025/26, 4% for 2026/27 and 5% for 2027/28.