The steering wheel robot is the steering wheel of a Cadillac Escalade, transformed into a creepy Transformer with spider-like limbs. It was given life when Sam Witwicky accidentally dropped the All Spark. It seems to like its owner and hugs her face.
"Did that jerk just dent my car?!"
When Sam accidentally drops the All Spark while fleeing through the streets of Mission City, he bumps into a woman's car. She is angry, and believes he dented her car. This is forgotten as the steering wheel of her car develops spider-like legs, wrenches itself free from the steering column, and clamps itself onto her face, hugging her head while she lets out muffled screams. It is unknown if the whole car was affected by the dropped All Spark or just the steering wheel alone, and whether the woman survived the ominous face-hugging steering wheel.
After the battle, the Autobots and Lennox's soldiers most likely locate the steering wheel bot, but it isn't shown, which means the steering wheel bot could still be alive.