Mt receipts are in a folder in the house, along with my spare pocket protector.

 

I also use a three ring binder with page protectors for each receipt but also have a spreadsheet that I update as well. I keep a printed copy of this at the front of the binder. It has the maintenance description down the left hand column and the mileage across the top. I place the cost of the maintenance where the two intersect. It doesn't take long to update and it gives me a quick reference of when my next service needs to be done and how much I have spent on my car. The binder stays in my office.