“Lumbar support is important. If your car seat does not supply enough lumbar support then an in-car lumbar support can be purchased.

• Automatic cars place less strain on the back as constant clutch use in a manual places pressure on the lumbar discs.
• If you only find you get back pain on longer journeys, don't try to complete the journey in one go.
• Stop regularly, get out of the car and move around.
• After long periods of driving your back is weaker and more susceptible to injury, so resist the temptation to bend and stretch.”

http://www.sportsinjuryclinic.net/sport-injuries/low-back-pain/back-pain-and-driving

http://www.jointessential.com/simple-tips-to-prevent-back-pain-when-driving/