Google overdelivery

Google overdelivery
According to Google’s documentation, they allows more clicks on your Adwords every day more than the daily CPC.
Google may allow up to 20% more clicks in a day than your daily budget specifies. We call this
overdelivery. Overdelivery can help make up for days when traffic is slow and your ads don’t get as much exposure. However, in a given billing period, you’re never charged more than the average number of days in a month (roughly 30.4) times your daily budget.

In general, a higher maximum CPC bid can allow your ad to show at a higher position on the
page.