For context, https://www.ons.gov.uk/employmentandlabourmarket/peopleinwor... says average weekly UK earnings are £643 (£33,436pa), or £689 (£35,828pa) including bonuses.
~10mph over the limit = 75% of your weekly income.
~25mph over the limit = ~150% of your weekly income.
I think it should include + ((weekly income)^2)/N because R > G.