£4000 wouldn't persuade me to go BYD. It might for others.
I'm on a phone but quick look at EV database (UK site), select BYD and Tesla, order by price/range and Model 3 comes out ahead of byd seal long range AWD, but RWD seal is ahead.
Many will be company cars, leases, so residuals will be important to monthly costs.
In some markets, the distributors are price gouging.
From Australian website, so AUD prices
Servicing is required every 12 months or 20,000km – BYD distributor says the first eight services are priced at $189, $370, $189, $447, $189, $370, $189, and $447 respectively.