How to overcome duplicate title tag issue on a classified website

How to overcome duplicate title tag issue on a classified website

I have an Automobile classified website.If someone submit an ad for my
website,the heading of the ad automatically generated from the
"make","model","registered year" and a custom text like follows,
Make:-Toyota
Model:-Corolla 121
registered year:-2005
generated heading: Toyota Corolla 121 REG-2005 for sale
Make:-Nissan
Model:-Sunny N16
registered year:-2006
generated heading: Nissan Sunny N16 REG-2006 for sale
And I used this heading as my title tag on the individual ad page.
I have used this method for sometime.
But now those pages are listed in Google webmaster tools with duplicate
title tags,because there are plenty of ads containing same make,model,and
year
Does it make any sense if I use any random id along with the heading to
make ad heading unique.If I do so, will it effect me to blacklist from
google? OR what is the best practices to overcome this issue. Thanks