Will this go away on it's own? It's been almost two weeks and it's still there. I've been airing out every other day when the weather permits but it hasn't been too sunny.

 

What kind of car shampoo was used? Did you use it or was it used from a detailer? When you say car shampoo I am thinking car wash shampoo but you may be referring to car carpet shampoo, is that the case?

here is the first method I would try
Deodorize the entire car. Once you've cleaned the car and looked for particular odors, consider doing an overall deodorizing of the car to try and finish off any lingering odors. Here is what to do:
Armed with a spray bottle of a quality odor neutralizer, begin by opening the hood of your car in a well-ventilated (preferably outdoor) location.
Start the engine and set the parking brake for safety. Next, place the AC (air-conditioning) and fan on full. Important: make sure the "fresh air/recirculate" setting is in the "Fresh Air" (outside air) position.
Go to the front fender side of the car (usually the passenger side) and look in the engine compartment. Find the AC/heater "Air Intake", sometimes called the cowl vent. Different vehicles use different air intake vent configurations but all are just below the bottom edge of the windshield, normally on the passenger side, and all have some sort of screen, grid or louvers covering the intake.
Liberally spray the deodorizer directly into the intake screen.
After a few sprays, get back in the car and smell to determine if the deodorizer is circulating through the AC system.
Repeat if necessary. This application should treat the air conditioning evaporator, blower, and ducting, the places where smoke and odor particles will collect.
Now, switch the AC/heater control to "Full Heat", leaving the engine running, the air control in "Fresh Air" position and the fan on full.
Go back outside the car and repeat the spray treatments into the air intake as you did earlier.
By switching to the heat position, the deodorizer is now treating the heater core, blower, and ducting, another place that odors will hide.
Repeat spraying if necessary.

After other cleaning options have been exhausted, use an ozone generator to do an ozone shock treatment to the vehicle. This will actually kill bacteria and mildew and denature odorous organic compounds. Read How to do an ozone shock treatment on a vehicle for details on what to do. see below

http://www.wikihow.com/Do-an-Ozone-S...t-on-a-Vehicle

seek professional help if all else fails. good luck

 

Wow thanks for all that info. I got my interior carpet shampoo and it smells very strongly of the chemicals they used. It's been a few weeks already and the odor is still lingering. It's good when I air out but it's pretty cold here and it's been rainy so after I have the windows up, the odor is back. It's been making me kind of sick and weak since I have chemical sensitivies.