My next door neighbor made it for several years after he found a clean used older model Mercedes for $1500.

He's a scrapper...

Picked up a used 250 gallon heating oil tank for free to store his fuel.

Went to the local transmission shop and picked up several clean 55 gallon barrels and then went to all the local fast food places and offered to remove their old cooking oil for free. Every time the barrels were full they would call him and he would pick it up and drop off another one for them to fill.

His equipment to make the fuel was simple...

He built a strainer out of screen wire and cheese cloth to remove the heavy crud from the "fuel" then pumped it through several large diesal fuel filters and a water trap. The finished product was cut with a little alcohol and fuel conditioner.

The car ran perfectly, no problems starting...fuel mileage was good.

I hated that Mercedes...made me hungry every time it was running. Smelled like a french fry factory.