Pull off the road to a safe spot to jot something down. Let your wireless network's voice mail pick up your calls when it's inconvenient or unsafe to answer the car phone. You can even use your voice mail to leave yourself reminders. Be a wireless Samaritan. No wireless service is perfectly secure, but the wireless industry has made significant investments to thwart eavesdroppers and phone-number thieves.
Slim batteries weigh less and provide less talk time and stand-by time than extended life batteries.
Slim batteries usually cost more because the battery cells are usually more expensive. The battery learns to charge only part-way if it is continually recharged before being discharged completely. NiMH batteries are less prone to memory effect because of a different electrode structure, but they still must be charged in an appropriate manner. NiMH offer slightly longer talk time than NiCad. However, NiMH batteries do not perform well in extreme temperatures and discharge significantly more quickly that NiCad when they are not used.