Obtain CDs specifically made to learn English. The most common format is stating a word or phrase in the native language and then repeating it twice in English. Avoid formats that are more complicated, such as extensive grammar lessons, as they may be harder to focus on while driving.
Take 15 minutes to review the printed material corresponding to the lessons you will be listening to in the car. Do this before you start driving. Since you will see the words and phrases before you hear them, it will help reinforce their spelling, pronunciation and your memory of them.
Repeat the English phrases you hear on the CDs. Rewind the CD if necessary, but only when the vehicle is stopped, to avoid being distracted from driving.
Turn on music in the English language when you need a break. This will help prevent your brain from becoming overloaded, while still reinforcing the language in an enjoyable manner. Insert a CD if you do not have access to English language stations.
Listen to the audio CDs every day. Consistency will help you pick up the language faster. You may also want to review the lessons you listened to after you are finished driving, as well.