Say a diesel powered car is $5K more then the gas version. The diesel gets 35MPG and the gas gets 24MPG, with diesel costing $4.20 and gas at $4.05. How much do you have to drive to make the diesel more cost efficient.

I have not problem with diesels and would gladly drive one, but some people would look at the numbers and be turned off. I would use the above argument to go against hybrids.