800 dollars gets you a nice new bike 800 dollars gets you a old car that might break down. I used to bike on 55 mph roads and I use to get passed by red necks doing more than that. Some of them were volunteer firefighters protect and serve bull****. Anyway I would go with the bike even if you don't spend money on a nice new bike you can get an older bike and save the coin for a rain jacket and accessories. Not really sure what your job is or wellbeing is I really wouldn't worry about commuting affecting your health or energy levels it isn't like your riding the TDF to work. Really who wants to drive a car that might break down or the doors might not open.

Regards