Try our Dodge Dart, same year:

https://oldcarbrochures.org/United%20States/Dodge/1964_Dodge/1964-Dodge-Dart-Brochure-Int/slides/1964_Dodge_Dart_Int-06-07.html

or that its somehow related to the Mustang ? P51 was the code of the WW2 fighter of the same name

Ddey65 : not sure what you mean by dead link , they both work fine for me and thanks for the US Valiant pic , definitely not the same !

Something like a Fiberfab Valkyrie - unconvincing GT40 lookalike?? The P51... means 351??

That last link is dead, and our '64 Valiant wagons aren't like the ones you have north of the border;
https://commons.wikimedia.org/wiki/File:1964_Plymouth_Valiant_(18362824801).jpg

In the meantime, this Ford-powered front engine sports car is a mystery too. It has a stripe along the bottom reading "P51x..." I can't see the rest of the number behind this guy's leg.
https://commons.wikimedia.org/wiki/File:Atlantic_Nationals_Antique_Cars_(3536358- 2145).jpg

you were on the god track..
seems to be 1964 Valiant wagon https://mystarcollectorcar.com/1964-valiant-wagon ( they call it canadian Valiant but i don't know if there was any difference with the US one )
flickr page has additional pics https://www.flickr.com/photos/annrkiszt/3445724797/in/photostream/

I originally thought this might be a Plymouth Valiant or a Dodge Lancer;
https://commons.wikimedia.org/wiki/File:Draggins09_073_(3445724573).jpg
I'm not so sure what it is anymore.

Thanks!

late Saab 9-5
https://www.carsautobuyer.com/used-vehicle-2011-saab-9-5-turbo4-premium-c-1959.htm

Can anyone identify the grey sedan in the background of this picture?

Nvm