The first picture of the green Smart shows the attachments I was referring to for the e-track. They are those short straps that he hooks his ratchet straps into. Can't tell how he hooked the front straps to the e-track. Maybe Smart's are very light? I just don't think e-track is that strong to trust a car to. I'd much rather have some large d-rings through bolted to the floor.
Here's a shot of the hooks I put in my trailer. Sorry I didn't take any pictures showing the underside, that's where the magic takes place. I got 4" aluminum angle (my entire trailer frame is aluminum). I cut sections of it about 5" long. I placed the piece of aluminum angle against the side of a trailer cross beam, under the decking of the trailer. Held up tight to the bottom of the wood decking. Clamp it to the cross member, drill two holes and bolt through with grade 8 bolts, and machine lock nuts (not nylock, machine lock have a slight peen over on one side of the nut making it stay put when you tighten them up). That way I could tighten the bolts until just starting to pinch onto the cross member and not have to crush it, and the nuts won't loosen. Then, drill the holes down through the floor and through the new angle plate. Then bolt the hooks on, again using grade 8 bolts and machine lock nuts. These baby's are strong! I got the d-rings at the wrecker supply store where I got the California roll back strap kit.
