Rumblestrip - Autobot Skirmisher

Rumblestrip: "Male" Cybertronian Robot (Transformer, Powermaster)
CR: 8     Huge Construct (Shapechanger)   HD: 6d10 plus 40     Hp: 75
Init: +4    Spd: 50' or xxx in vehicle mode    AC: 24 (-2 size, +15 Natural), t: 8, ff: 24
Attacks: (BAB +4/Grap +22); +12 Slam 1d8+10 (20/×2) or +2 Particle Beam Rifle: 8d6 (20/×2, 75', single or autofire)
     * Autofire targets a 10'×10' area, Ref DC15 to avoid
SA: Alternate Form
SQ: Cybertronian Durability, Cybertronian Traits, DR10/--, Powermaster Traits
Align: CG     Saves: Fort +2, Ref +2, Will +3
Str: 30, Dex: 10, Con: --, Int: 13, Wis: 12, Cha: 10
Skills: Read/Write and Speak Common and Cybertronian; Computer Use +11, Disguise +10 to appear as a normal dragster; Drive +9, Knowledge (Technology) +10, Navigate +6, Repair +5
Feats: Advanced Firearms Proficiency, Heroic Surge (b), Improved Initiative, Personal Firearms Proficiency
Gear: Particle Beam Rifle

Advancement: by Character Class

ECL: +8

Height: 18' (Robot Mode)     Weight: 2,320 lbs.
Length: 25' (Vehicle Model)     Eyes: Green

• Alternate Form (Ex): Rumblestrip has two forms. The first is a giant humanoid robot with a narrow torso and long, thin arms and legs. A spoiler rises from his shoulders. His second form is that of a bright yellow and orange Top Fuel Dragster. To transform from vehicle-mode to his robotic form, his engine ejects and transforms into a humanoid robot with exhaust pipes emerging from his back. This engine, Nitrous, then attaches to Rumblestrip's back. The long forward section of his chassis splits down the center to become arms and legs. The dragster form's front tires are attached to his wrists and his larger rear tires are located behind his shoulders. His head resembles a motorcycle helmet with a green visor.
     He gains a +10 racial bonus to Disguise checks to appear as a normal dragster while in his vehicle mode. 

Vehicle Mode:

Init: +2     Maneuver: -2

Top Speed: 540' (54)     Defense: 8

(I am not an artist but hopefully you get the idea)

• Cybertronian Durability (Ex): Cybertronians heal hit points and ability damage normally but are unaffected by Cure/Inflict spells. The Heal skill has no effect on them but they may be repaired through use of the Repair skill. A Cybertronian is not permanently harmed by the loss of a limb, its head, or other vital components (although it's functions may be greatly reduced). A body part may be attached or detached by making a DC30 Repair check (time determined by DM). A Cybertronian reduced to 0 hp ceases to function and stops healing but does not die unless its spark (typically a glowing blue crystal containing the Cybertronian's soul, usually located in the robot's chest) or brain module is destroyed by a specifically targeted attack. It can remain inert and unconscious indefinitely. It can be brought back from "death" by restoring its hit points to 1 or more.
• Cybertronian Traits: Darkvision 60', Low-Light Vision, Immune to Poison, Sleep effects, Paralysis, Stunning, Disease, Death and Necromancy effects, any effect requiring a Fortitude save unless it affects objects, Nonlethal Damage, Ability Damage/Drain, or Energy Drain. Unlike other constructs, he must recharge (sleep) and consume crystallized or liquified energy. He has many delicate systems and is subject to Critical Hits. He does not need to breathe and can survive comfortably under water or in a vacuum.
• Powermaster Traits (Ex): Powermaster partners are able to filter and counteract the radioactive toxins within Nebulan fuel, allowing a Transformer who has been poisoned to function normally.
     A Powermaster partner can also function as a power booster or turbo accelerator, giving the Transformer he is bonded to a surge of additional power for increased strength or speed in dangerous situations. They gain Heroic Surge as a bonus feat.
     In addition, a Powermaster engine is more adaptable and efficient than a standard Transformer fuel cell: far from requiring energon or refined fuels, Powermasters can run on almost any energy source - including food. This makes it much easier for a Powermaster to adapt to the available resources, without needing to waste time or energy converting them into a more palatable form. Powermasters must consume exponentially more food and water than normal to maintain its Transformer host, as noted: Large (×2), Huge (×4), Gargantuan (×8), and Colossal (×16). Failure to eat and drink the necessary amount, they begin to suffer the effects of starvation and dehydration.
     Over time, the bonding procedure for Powermasters seems to be similar to that of some Headmasters, in that there is a risk of both partners being absorbed into a single being with only one mind and identity. Every day, the Powermaster must make a Will save (DC15) or be subsumed by its Transformer.
     Additionally, a Transformer needs his bonded partner to function. Without them, he cannot transform, fight, or even move. His partner is basically an advanced form of life-support, and should they be lost, killed, or even damaged, the Transformer will be in mortal danger.

(Made this on Google AI)

Using Rumblestrip in Your Campaign: This character obviously fits best into a modern or even futuristic setting but it is possible, given that the Autobot Ark crashed on Earth four-million years ago, it is possible that one of its passengers was awakened earlier than what is revealed during the original comics or TV series and set out to explore the new world around them, giving rise to legends like Talos, the bronze giant who protected Crete from pirates and thieves in Greek mythology or Cacus, a fire-breathing giant from Roman tales.

OR

A new racer is making a name for himself on the drag circuit. But nobody has ever seen the driver without his helmet. The party is hired to investigate the matter, secure an interview with the mysterious figure, and get pictures of him. They soon discover that there IS no driver, the car is a sentient vehicle that is able of turning into a giant humanoid robot fighting in a war against other robots.

OR

A one-shot based on "The Iron Giant". The patty could be townsfolk who have befriended and are protecting the "giant" or a member of the military who have been sent to investigate and neutralize the threat.