Is charging in car recommended? Does it affect the battery?

Charging the phone in the car affects the battery in as much as it increases the charge and, while plugged in, doesn't use the battery. In other words, it affects it exactly the way charging it by plugging your phone into the wall or into the computer does.

I recommend a good quality charger no matter what you're plugging your phone into.

I recently got a vent mount for my car that has a MagSafe charger. It's great.

In addition to IdrisSeabright's reply, one thing to take into consideration is Qi wireless charging. Some newer car models offer this option. Wireless charging does introduce some heating affect and coupled with a hot vehicle interior could possibly affect overall battery life. However, this shouldn't be an issue for non-wireless chargers.

I've seen a few posts here about vehicle wireless charging and just wanted you to know.