Transformers: Autobots and Decepticons/Vehicle Forms

One of the features new to the Transformers series is the ability to scan human vehicles and use data from them to change your form; in previous games and other media a transformer's alternate form is essentially permanent after choosing a scanned vehicle or lifeform to mimic. For some story missions you play as other transformers; they are not able to alter their vehicle mode, but scans done by them are still stored and can then be used by your primary character.

Here is the complete vehicle list arranged as it appears on the Vehicle Form menu, followed by where to find it. Vehicles marked as "(hidden)" aren't found just anywhere, and must be scanned during the appropriate mission. Some vehicles are exclusive to a particular version, but most are available in both versions.
 * Beater - available from start
 * Sportster - available on the second visit to Tranquility
 * SUV - available on the second visit to Tranquility
 * Armored Truck - available on the second visit to Tranquility
 * Chopper - during "Follow That Convoy"
 * Notchback - available on the first visit to Tranquility
 * Import - available on the second visit to Tranquility
 * Attack Copter (hidden) - found in small base at Hoover Dam
 * Peace Van (hidden): found near the dam during the Hoover Dam mission
 * Pickup - available on the first visit to Tranquility
 * Utility - available on the first visit to Tranquility
 * Pickup Car - available on the second visit to Tranquility
 * Moving Truck - available on the second visit to Tranquility
 * School Bus - available on the second visit to Tranquility
 * Longhorn - unlocked with 250 WiFi tokens
 * Gunner - unlocked with WiFi tokens
 * Flame Truck - Available on the second visit to Tranquility
 * Ice Cream Truck - Available on the second visit to Tranquility
 * Recon Chopper - Available on the third visit Tranquility
 * Lightning Rider - Available on the second visit to Tranquility
 * Death Truck - available on the second visit to Tranquility
 * Tricked Out Car - available on the third visit to Tranquility
 * Funky Bus - available after signing onto Allspark Wars for the first time
 * Racer - available on the third visit to Tranquility
 * Maintenance Truck - simply complete the game once
 * Hot Rodder - Available on the second visit to Tranquility
 * Stealth Chopper - found during "Happy Landings"
 * Safari Truck (hidden) - found at a campsite near the water at Hoover Dam
 * SWAT Van (hidden) - found near the Buggy during "Know Thy Enemy"
 * News Copter (hidden) - found on the Casino Strip rooftop
 * Off-Roader - available on the second visit to Tranquility
 * Raider (hidden) - found near the docks in Tranquility
 * Speedster - available on the third visit to Tranquility
 * Police Copter - available on the second visit to Tranquility
 * Transport - unlocked with WiFi tokens
 * Prison Bus - available on the third visit to Tranquility
 * G1 Skydive (Transformers: Autobots only, Download Station exclusive)
 * G1 Starscream (Transformers: Decepticons only, Download Station exclusive)

Download Station exclusives
Each game features a G1 character that can be unlocked by visiting from the Download Stations at Target and GameStop. At the moment, there is no known alternative for unlocking them (except possibly with Wi-Fi tokens).

To get your version's exclusive jet, do the following:
 * 1) Move close to the Download Station.
 * 2) Turn on the DS.
 * 3) Choose Download Play.
 * 4) Open the Transformers file that appears.
 * 5) Watch the Transformers game video.
 * 6) The video plays on the top screen; the bottom screen will say "BONUS CHARACTER UNLOCKED". Once you see this confirmation screen the exclusive character is yours to keep!
 * 7) Go into the hover dome and turn around and you see a jet. Scan it and it says "jet unlocked".