Remind them that after getting their permit (if they are 14 1/2 to 16 1/2) they need to do a mandatory 6 months of supervised driving with a licensed driver 18 or over. This means no going to the movies with friends or taking out a date.
Try to get them thinking about all the cool things they can do with a drivers license. This could be going to the gym by themselves, dates, sporting events, school events, concerts, shopping, road trips, comicons, hunting, whatever you can think of. Plant some thoughts into their heads. Trust me - they'll think about it.
Talk to them more and more in the car when you take them places. I would love to have someone drive me places and pick me up as long as I have my smartphone. Constantly talk to them - don't purposely bug them - just ask them questions that interupts their thoughts. They'll gradually get tired of it and want to drive on their own more and more. The funny thing is when they drive they won't be able to use their smartphones anyways (hopefully).
Telling them that as soon as they drive they're buying gas and insurance is not a very good incentive. Because it basically means they'll have to get a job. Provide a better incentive like "maintain a B average and I'll give you $20/week gas allowance". Or combine it with "don't get in any wrecks or get any tickets and I'll pay your insurance". This might cost you money but the benefits are great - you'll have great leverage to help keep good grades and they'll drive safer. Keep in mind any time a young person gets behind the wheel, there is a chance of something happening. If half of their driving is to work, which is required to pay for gas...of which they're using most of it to get to work; and they're driving to work to pay for insurance of which they'll need when they get into a wreck driving to work - are they really getting ahead. And usually the more a student works in high school and college the worse their grades are.
Please remember that to get the most out of driver education the student needs to want to take drivers ed. Student who don't want to take drivers ed, usually don't learn very much.