Caculating car and truck expense on schedule C

[vrgr79wild]

It looks like there are two possible methods that can be used to figure this expense, a rate per business miles driven or using actual expenses. 

1) Is there any requirement to use the same method every tax year?

2) Actual expenses include gas, repairs, insurance, license plates and other taxes, etc.  Correct?    ( The vehicle I am talking about is old so I do not plant to use deprecation as an expense. )

3) Is the expense amount to use equal to the actual expense multiplied by the percentage of business miles divided by the total vehicle miles? For example:  if the business miles, i.e. business miles + commuting miles, are 7400; the total miles are 14800; and the actual expense is $ 800 then the amount to enter on line 9 of the schedule would be $ 400.

The calculation is: 7400 divided by 14800, the result is 50 %. Then 50 % of 800 = $ 400.

Correct? 

4) Any other things need to be considered? 

Thanks very much for your help.