This ad is a Canadian 'Spoof' ad that I believe ran in the mid 60's (possibly 1965). If you aren't/weren't familiar with the ads it refers to in the text it is difficult to identify the humor. Below is the complete text for this ad with links to the ad/s it references. Have fun!Look.
We're busy.
"It takes us four times around with the spray can before we get the paint right."
"Our inspectors don't help any."
"(They think we've got nothing better to do than wipe their chalk marks off cars all day.)"
"An old guy in Wisconsin keeps grumbling about lousy oil consumption."
"Our stylists keep handing us this line about wanting to draw something."
(Next thing you know they'll be demanding pencils and paper.)
So who's got time to bother with heaters?
Wear an extra overcoat.