Enhanced CPC is a new bidding feature that automatically raises and lowers your Max CPC bids each time your ad is eligible to appear based on the likelihood that your ad will convert.
For each auction, Enhanced CPC calculates a predicted conversion rate using your historical conversion data & a number of other factors.
If a click is likely to convert, the system increases your Max CPC bid. Note that the system may increase your bid by up to 30%. If a click is unlikely to convert, the system will lower your Max CPC bid.
Enhanced CPC monitors its impact on your campaign, so a campaign should perform the same or better than had you not turned on Enhanced CPC.
Enhanced CPC is a good intermediate step for advertisers who want to take advantage of our automated optimization technology, but are not yet ready to adopt Conversion Optimizer.