Company mileage - EV on Salary Sacrifice scheme

Hi, My understanding is that HMRC consider a Salary Sacrifice vehicle as a Company Car and as such only AER can be claimed free of tax (I personally think this is unfair as I am still self-funding the vehicle). My Company is offering all employees making business travel the AMAPS figure of 45p per mile. I further understand that I can claim an extra 5p tax-free when accompanied by a colleague. Therefore, when unaccompanied I understand that i will pay Income Tax on AMAPS - AER (45p-8p=37p) at the Tax rate (eg. 40%) and therefore the effective ppm will be = 8p + (37 x 0.6) = 30.2 ppm and when accompanied Tax on AMAPs - AER - 5p = [45p - (8p + 5p) = 32p], effective ppm will be 8p + 5p + (32*0.6) = 32.2 ppm 1st question : Is this correct ? 2nd question : I am on SA, please could you provide advice on how i report this and therefore pay the appropriate Tax ?

Hi,
You can use the HMRC tool to calculate the value of the company car: 
Calculate tax on employees' company cars
Then you can use this link to calculate your income tax:
Check your Income Tax for the current year
We are unable to offer financial advice. 
Thank you