You could try a dedicated interior cleaner or dilute some APC (all purpose cleaner) at 1:20 or so. Car shampoo can be kind of gentle and isn't strong enough to remove stubborn stuff.
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Stillen Gen3 CAI|Berk HFC and CBE|UpRev|15mm H&R front spacers|20mm Ichiba rear spacers|Stillen front and rear sway bars|Yokohama S. Drives|Swift springs|JDM Blinking Fog|8000k HIDs|9% window tinting, 47% on full windshield
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