Ok, this is common misconception about the EV Credit. The term has nothing to do with owing money in Apri, or your refund check from overpaying in taxes. The credit can be received in full, or partially:
If the EV credit max is $7,500: Non-Refundable Credit means if your Federal Total Tax liability was only $7,000, then you can only receive a $7,000 credit. The $500 credit that you could not utilize is GONE, it cannot be refunded to you. Some federal credits ARE refundable and any portion which you didn't utilize is sent to you regardless.
For my 2018 tax return, when buying my Model 3, I got a refund check for $12,000....$7,500 EV credit + $4,500 from the IRS from overpaying taxes.
1) AGI has nothing to do with Total Tax liability. We are explaining how that works. AGI is a separate requirement. Anyone making $50k or more is probably paying $7,500+ in Federal total taxes.
2) Leases - If you lease an EV, the lease company gets the credit and they apply the benefit to you, the leasee. They either give it to you as downpayment cash (not Tesla) or they use the money to inflate your resale value (reduces depreciation), which lowers your monthly payment. So yes, you get a benefit as a leasee.