Not that it makes a whole lot of difference because 50-60C is the same all over the world but, where is this part of the world?
Thanks for all the replies. I was mailny curious to see if I could just leave the camera in the car all year round but it sounds like it will be best to take it out of the car during the warmer months and keep a cooler bag handy for those trips on warm days when I do decide to take it with me.
Heat is especially bad for lenses. As Anscojohn mentioned, lubricants get less vicous at high temperatures and start to bleed into areas they aren't supposed to be in. If helicoid grease gets into your aperture blades on an SLR lens, you can forget about your lens stopping down properly. This will cause overexposure of your images, unless you always shoot wide open. I can only guess that there are lubricants in other areas of the camera, too. If I need to leave a camera in the car, I put it in a dry cooler in the trunk. The trunk stays cooler than the rest of the car, and the cooler is insulated, so it should maintain a lower internal temp than the rest of the trunk. Even in a cooler, though, the inside temperature will eventually rise to the ambient temperature of the trunk. I do not put ice in my cooler. You do not want to take a camera from a cold environment into a warmer one, especially if there's humidity. This will cause condensation, which is probably faster and more deadly to electronics than heat.
And even a few hours of exposure to heat over 50c will damage your film.
Film is damaged long before 50°c i.e. casts, streaks on emulsion where film rails contact etc. Besides all this, why would you leave a camera in a hot car, or anything of value in a car? Remove it. Only tempts thieves anyway.