Why do most cars not have any hood vents? In the summer the temp under the hood is very high. (If you want proof, just raise the hood after a summer trip)
Wouldn't it make more sense to design hood vents into every car? Wouldn't the entire under hood area benefit if the max temp was significantly lower? I had a Datsun 280Z and it had a hood vent. It was designed not to let rain water come in.
Installing one myself would be costly, require some repainting, and prone to rust.