You can pretty much take it as a one for one: $US to £GB. I know it doesn't work out that way in the financial markets but cars in the US are about half of what they are over here in financial terms.

So I bought my SRT6 as a delaer demo with 3500 miles on the clock with a free first service and one free of charge replacement to the rear tyres when needed. List on the SRT6 in UK was £33,500. I did the deal for £24,000.

From threads I have seen, $23-$24k is pretty much par for the course in the US for the equivalent, maybe even less. One thing though: in the UK, what you see on the forecourt is what you pay. All taxes, including 1 year's road tax, are included in the ticket price.