This was item # Item 2336 at hakes.com which is a collectibles auction site.
Bidding started at $400 with no bids received by close of auction. Description on their site was as follows:
22.5" tall (to top of steering handle) by 25" wide by 37" long pressed steel body riding toy by Mattel ©1966 National Periodical Publications Inc. Reworked Mattel Zoomcycle, this has "Batman" specific labels including "Batman" logo as well as "Batmobile X-15" side labels and batwing-like accent labels for back of seat and "Dash" label which reads "Hi-Rev X-15 Batmobile." Original dark blue paint. Adjustable seat, complete with original embossed seat belts which are almost always missing. All decals are present, 40% of "Dash" decal is missing. Pedal-driven toy whistled when ridden. Long steering lever adjusted back set of wheels and proved very difficult for children to ride, more than one tipping toy over. Labels show wear, back batwing missing about 35%. Lt. wear from use but no rust. VF+. Extremely difficult to find this nice. From the Craig Warren Collection.