Hello insight: Perhaps I can help with your garden

A few questions.

What is your rainfall? Does the rain fall in a predominant season? What is your soil type? Roughly speaking where are you? Snow ice desert flood plain??

Site history: I read the cars and trucks mechanic's history of your yard - is that all? Freon is not likely to be an issue.

In your locality can you find any good gardens and gardeners? Both are of great value. They can often teach about local conditions and requirements.

To your situation specifically. You mention "dead soil" what do you mean? Do you have a small area where you can start a garden trial? Can you have a look around with a spade? There may be more life than you realise?
In many old car yards in Australia (where I am) there is not a measurable increase in soil contamination from those activities.

A process used in Australia is to break the soil, Spread blood and bone with any lime etc required, spray with a Sugar and microbial solution then mulch and plant a grass mix after the mulch starts to Break down. A similar process is used in contaminated/degraded farming sites where excessive herbicides have been used causing a collapse of soil microbial activity. T2