The black tweed in these cars usually looks grey, sometimes you have to take a second look to see if it's black. The vinyl and plastic parts are easy - semigloss black MM or Tamiya, flat for the carpets. The cloth seat inserts would be the tricky part, they looked darker when brand new, but faded to a charcoal greyish color when a few years old. I think you're on the right track with fogging on dark gray from several feet away, but it may look too dark to register right; so you might try a grey primer fogged on the same way. I did test shots on scraps to get the look that I was happy with, I would do the same with the black to get the level of grey you want.
-MJS