You would not be able to claim a Energy Efficient Vehicle tax credit on a 2020 tax return if the vehicle is purchased in 2021.
See this website for eligible vehicles - https://www.fueleconomy.gov/feg/taxevb.shtml
The tax credit is used to reduce your tax liability (tax owed). If the tax liability is reduced to 0 then the remaining credit is forfeited, it is not carried over to the next tax year. You cannot receive more of a tax refund using the credit only the amount of federal taxes withheld plus any other refundable tax credits you for which you are eligible.
