Jen awoke to the usual tingling warmth and slight pleasure in her abdomen, as well as the humming fart noise of her anus mixing with her low exhaust note. As she sat up, yawning and stretching, her engine began to rev up, increasing the vibrations reverberating in her pussy. If she hadn’t been used to this from years of experience, she would’ve had a small orgasm just from that. This had caused her problems when she first started puberty, but she had since developed a tolerance to the constant stimulation, though she would still consistently work her way up to an orgasm due to the continuous vibrations, but she had greatly increased her endurance, though she would still orgasm every twenty minutes or so when she was up and about, but at idle she could last several hours.
Her silent passenger, on the other hand, was not accustomed to it, and her confusion as to what was happening and why she was trapped inside her own body was drowned out by the cacophony of pleasure she felt from her pussy. She desperately wanted to shove a hand inside and bring herself to orgasm, but her body refused to cooperate, as it got itself dressed, even her vision was out of her control, forcing her vision to focus on whatever the alternative version of herself wanted to. Her body grabbed a pair of cute pink panties with a heart-shaped hole in the back for her exhaust and pulled them on, leaving an exposed window in the back showing part of her crack and her anus, which was constantly forced open by the stream of gas expelled from it. Out of the corner of her eye she noticed the large vents in the ceiling designed to prevent the toxic gasses she expelled from filling the room and suffocating her and her mother. Not that she was even affected by the gas too much, with her lungs acting as little more than an intercooler for her engine, cooling the air before it reached her intakes. This made her chest unnaturally cold compared to the rest of her body, in contrast to her abdomen, which was impossibly hot to the touch.
Brushing her teeth, Jen rushed downstairs, where her mother was mixing her oil and gasoline in a bowl, careful to get the ratio just right so her daughter’s engine would run just right. She knew her daughter always loved a little extra oil to keep her running as smoothly as possible (which also helped reduce the vibrations which constantly stimulated her pussy.) She also poured her a large glass of ice-water, just to help keep her engine cool. Before she sat down, Jen quickly excused herself, rushing to the bathroom and sitting down on a bucket next to the toilet, before relaxing her internal muscles and allowing used oil to drain from her pussy and urethra and into the bucket. She opened the hatch on her abdomen just to admire the shiny metal device in her abdomen humming along. She wiped the oil from her crotch with a paper towel and threw it in the toilet. Since her used oil could be recycled, she always relieved herself over a bucket to catch the used oil, rather than literally pouring it down the drain by sitting on the toilet. With the amount of gasoline and oil her body went through, as well as paying to maintain her engine, she needed to save money wherever she could.
Sitting down at the table (at an angle so as not to obstruct her exhaust pipe) Jen picked up the bowl and began pouring the viscous, inky black fluid down her throat. Gas-powered Jen was used to the taste, but the normal girl along for the ride desperately tried to wretch as the foul concoction slid along her tongue, but as before, her body ignored any and all input from her, continuing to let the fuel-oil mixture fill her stomach. Wiping the black liquid off her top lip with the back of her hand, she let out a satisfied bubbling belch as the gas she had accidently ingested along with her fuel slowly made its way out of the pool in her stomach. Gulping down the water, she hugged her mother and rushed out the door, shuddering in the doorway as her engine surged to provide extra power to her legs. Catching her breath, she rushed out the door and runs to catch her bus.