Google Merchant Center seems to be rolling out a new reporting feature that lets you build your own performance report. You should be able to access this in the Google Merchant Center under the "Performance" tab.
Brodie Clark spotted this update and posted about it on Twitter. He said he is "seeing new reporting functionality (both paid/unpaid) in Google Merchant Center. Wasn't there previously, at least in Australia. From an SEO POV, allows you to create custom dashboards for Surfaces Across Google data."
He shared this screen shot (click to enlarge):
Here are the steps to set up your own new dashboard in Google Merchant Center:
1) Sign in to your Merchant Center account.
2) From the navigation panel, click Performance, and then Your reports.
3) At the top of the screen, click the Your dashboards tab.
4) Click the plus button .
5) In the top bar, click the pencil icon Edit to name your dashboard and, if you like, add a description.
6) To add a report or scorecard, hover over a cell and click the plus button or the plus icon in the grid box.
a) To add a report, choose New report or Existing report. If you click New report, you’ll be redirected to the report editor. Note: you may only use custom reports that you’ve created.
b) To add a scorecard, click Scorecard.
7) Repeat for any other reports you’d like to add to this dashboard.
8) Click Save.
Forum discussion at Twitter.