So, HHR is modeled after a 53 Suburban?
 

This is a 57 Minor, looks real familiar.
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The HHR was modeled after a 49 and the Minor mimicked the American designs of the late 40's and early 50's

There were several British cars that looked as 2/3rd scales American cars back then. The British industry was recovering from WWII and they borrowed a few ideas till they got back on their feet in the 60's.