Looker

 From this end it looks good.

For the record ...

For the record, I don't use ONLY the weathering powders when I weather, and many times I don't use them at all on cars. Just depends on what you're after. I also weather with a brush and acrylic paints. Watch the tunnel portal video again - notice I first weathered the portal with acrylics, then added a dusty final layer of weathering powder.

Most cars weather in streaks from running crud in rainwater, not blotches, so brush down on the weathering you've applied to this car with a damp stiff brush. If the weathering comes lose after it's dry, try hitting the car with some dullcoat to fix things in place. The dull coat will make the effect of the weather a lot more subtle.

Damp stiff brush, got it.

Great tip, thanks! 

Bye the way, didn't mean to insinuate that was all you used - I simply wanted to try them on rolling stock as is to  see the effect.

Final results

I hit the model this morning with a stiff damp brush, as Joe suggested, using vertical strokes. The end results?

I think pretty good! Note I have not used dullcoat on this yet.

Here's the before

Thanks for all of your help, Joe.

Another (successful) Test)

Another successful Test

Before

Another Test

I'd say that was a success!  The weathering looks fabulous!  Mother Nature could not have done better herself!