Sounds to me like you're doing things right and doing all you need to do. Documentation is the key and you seem to have that down. But when reporting/claiming the vehicle use that first year, work it both ways to see which works best for you. So figure the "actual expenses" method first, since you have all receipts, including gas receipts. Then do the "per mile" deduction. My bet is, you'll come out better with the "per mile" deduction. But it really depends on the total miles driven for the year, and what percentage of those miles are business miles.
Do note that if the vehicle is not 100% business use, then you have to claim the "per mile" deduction.It's practically impossible to prove how many drops of gas in a tank were used for business, and how many were used for personal use.
