I know next nothing about this, but it may be of some use to a few of you in the Dallas, Houston, Austin metro areas. "Is your car or truck 10 years old or older? Or has it failed an emissions test? You may qualify for up to $3500 toward replacing your vehicle" http://www.tceq.state.tx.us/implementation/air/mobilesource/vim/driveclean.html (This is limited to certain metropolitan counties and is income-restricted.) It seems you have to 'retire' the old car - but lots of guys have donors they send off to the scrapyard when done, so maybe there is an angle to work here.