I'm in sales for a small copier company. We are paid $0.15 per mile. (We can claim the rest of the allowed amount on our taxes.) Regardless of the compensation plan currently in place, the high gas prices probably negate the original intent of the company. Most sales personnel are probably spending more than their compensation plan allows, especially if you take into account the maintenance (oil changes, tires, etc.) and the wear-and-tear on the car.
You're right about the freight cost on DMAP, but it probably does affect the sales personnel as well. We add freight into our cost...higher freight means higher cost and lower profit -- which in turn means lower commission for us. We both lose when freight cost is high.
Yes, I understand the company is getting hit, but they are not alone, and I definitely would not say it's "quite the opposite". The double-whammy hits the sales staff just like it does the business owner.
Profits are lower for all of us, and I, for one, appreciate ANY attempt my company makes to help ease my burden. I think offering an increase in gas allowance would be a great gesture that would be appreciated.
The price of gas has doubled, and I'm sure you can't afford to double their gas allowance, because your cost has increased as well. Any increase you would be willing to do will most definitely be appreciated. Since your question is worded like you own the company (or are at least in management), you are to be commended for your consideration.