The car smells like sulfar when I drive it it a hill.
It would seem that exhaust is entering from the rear of the vehicle. Has the vehicle been involved in a collision?
No, it is very well taken care of. And is fixed when it needs to be fixed I think the valves might need to be resealed.
This has nothing to do with the valves. The exhaust valves open many times each minute. Leakage can’t equal the amount of exhaust that comes out when the valves open. The sulfur smell comes from the chemical compounds formed when the gasoline is burned. The catalytic converter is supposed to eliminate the supfur compounds. If you smell sulfur, either the catalytic converter is malfunctioning or the exhaust system between the engine and the catalytic converter is leaking.
Is the smell toxic? If not should I fix it?
For Pete’s sake , put this in a shop and have it fixed . You are not supposed to smell something like that so there is some thing wrong with the vehicle.
If you think something has changed than go to a shop.