This is my great grandfather, Robert William Johns. Unfortunately, the photo doesn't have a date on it. I don't know anything about cars or dating them. The Model T Showroom website has similar "looking" vehicles (based on looking at the windshield, radiator cap, tires and fenders) that are dated in the early 1920's. The website Ford T 1921 for Sale has photographs that look very similar. The Beefcake Swimwear: A visual scrapbook of vintage men's beachwear website shows similar swimsuit designs from the early to mid 1920's. Of course I can't determine the age of the vehicle or the swimsuit at the time the photo was taken, but I would guess late 1920's.
Looking at this photo always made my Dad chuckle, and I can understand why...I love those knees!