Mekgineer's Chopper is a motorcycle mount created by top Alliance engineers. This vehicle allows one party member to ride along in the sidecar. It's one of the few mounts that can be bought on the Auction house, however it will usually cost plenty of gold, considering the price of the mats to create it.
The Horde counterpart is Mechano-hog. Either one fulfills the achievement.
To activate Mekgineer's Chopper's sidecar and carry a passenger, simply invite the player to a group. The player's pointer will turn into a green mounting arrow when they mouse over Mekgineer's Chopper, allowing them to jump on while the sidecar deploys itself automatically. Note that if you are in a raid group, your passenger must be in the same group (1, 2, 3...etc) as you to enter the side car.
This item can be crafted using Engineering (450).
Taught by Exalted reputation is required to purchase the schematic., which can be purchased from the Alliance Vanguard quartermasters and for 320.
These components must be purchased fromat K3 in Storm Peaks for total cost of 12500 and are available for sale only to engineers able to craft this item. No reputation discount is available for these parts.
The two Arctic Furs are gathered by a Skinner.
The 40 Cobalt Bolts are created by an Engineer, and require (on average) 40. (There is some uncertainty. Each 2 cobalt bars makes 1-3 bolts.) Cobalt bars, in turn, are crafted on a one-for-one basis from by Miners.
Patch 3.1.0 (14-Apr-2009): This mount is no longer considered a vehicle.
Now fully a mount, with fall damage, instant mount/dismount, and swimming ability.