Only a small proportion of people can afford cars above £40,000 and it is fair that people who can afford the most expensive cars pay more.
Ordinarily I would agree with a progressive tax.
However, in this instance I take a different view. To get an EV with "decent range" you are going to have to pay North of £40K. So plenty of people who need to do long journeys (my personal example is 30K miles a year, of which probably 20K is business, and much of that is 100-150 mile journeys (each way) in a day), and who want to switch to EV to help the planet, are going to have to find the money some how. Some of those will be rich enough to afford it, and I agree the tax for them is not a deterrent, but (for example) the Tesla forum has plenty of examples of evangelists who are spending way more than they would ordinarily be comfortable with in order to be part of the green revolution. A short range EV, the type ideally suited to a metropolitan commuter, would be hopeless for me as I live out in the sticks. Equally being excused from paying the London Congestion Charge is of no benefit to me, as I have no occasion to drive into London, and so on.
So an upshot of taxing long-range EVs is to remove many potential buyers. Many of those, myself included, would not ordinarily spend £80K on a car, but with reasonable incentives will do so, and in so doing voluntarily create a demand for, and help the industry develop, longer-range alternative energy vehicles. Until the EV marketplace matures this needs to be done collaboratively between Government (i.e. subsidies) and members of the public willing/wanting to help.
Progressive / punitive "luxury" tax on longer range EVs will have the effect of encouraging car makers to concentrate on short range vehicles, and only local commuters will be able to use those.
If I'm talking Horse, and there are sub-£40K vehicles that have reasonable range, which are suitable for business drivers needing reasonable range on a daily basis, then I'd appreciate being corrected.
If not you are welcome to use my comments in any reply to the Minister that you choose to make (although I expect that the same thought has occurred to everyone else, so there is absolutely no need to quote me, as such)
In case this is quoted elsewhere, and in case not obvious, EV = 100% Electric Vehicle (i.e. NOT a Hybrid)