Rust on the rotors can be serious. If you let it sit long enough the entire rotor will rust away into a pile of red dust. Try jacking the car up and have someone apply the brakes while you turn the wheel by hand. This procedure can be done without removing the car cover. Do not drive the car. This may remove the rust but safe operation of the Viper will require the removal of the car from the climate controlled garage and probably the removal of the car cover. This will not only allow outside, unfiltered, air to contact the car but may cause fading of the paint when sunlight strikes the car. Be careful.