An optional feature that can help you get more value from your ad budget.
• ECPC raises your bid by up to 30% (after applying any bid adjustments you’ve set) or lowers it by as much as 100% each time your ad is eligible to appear, based on how likely that click is to lead to a conversion.
• ECPC modifies 50% of your traffic initially, and then moves that percentage up or down based on how it is performing.
• ECPC can help you to increase CPA
It does this by analyzing your campaign’s historical conversion tracking data along with a number of other factors. These include the individual words that make up the user’s query; the user’s geographic location, web browser, and operating system; and even time of day when the user is performing a search. You can get a full list of the factors that Enhanced CPC considers when predicting your conversion rate, from the AdWords Help Center.