AIUI there are a number of get out of jail clauses in the rules surrounding the % of EVs sold. In particular it is expected that companies will be able to trade quotas - thus Tesla (100% electric) will be able to sell quotas to other companies with inadequate EV sales.
As the fine is £15k per vehicle for failing to meet the quota, I assume this sets a cap on the value. I have no idea what the premium will actually be - probably less than £15k - but even £3k additional cost on ICE will mean £3k off the EV - difference £6k.
The simplistic impacts:
- the price of ICE vehicles will increase due to the price paid for EV quotas
- manufacturers of EVs will get a price advantage through selling quotas
- demand for EVs will increase
This has the potential to completely disrupt the car market - I expect over the next 2-3 years for a number of established manufacturers to disappear to be replaced by new entrants who have invested in EV capability - design, technology, manufacturing processes etc.