You can specialty order a car that is wheelchair accessible if you need it - but if you are one of those, you can't crap in the car - you'd just mess in the chair. The alternative is that her chair was in the trunk and she got in the backseat - but that also makes no sense, given that she somehow got in, noticed actual shit in the seat and somehow didn't mention it? And the driver didn't smell it? They can't even lie properly.