Lets' see.. Grande' sets back $5 a pop.. thats $25 per day if you have 5.. that's $750 per month.. approaching $10 grand per year.. approaching $100 grand in 10 years..
A grande of what is $5? How about getting some accurate figures there before you start playing Euclid. I get a venti drip and that's about $2. Americano is $3. It's cheaper than any local coffee shop and the pricing isn't different thank Dunkin'.
Starbucks is great on the road if only for the little green sticks that seal the lid of your coffee so it doesn't go all over the place as you drive. They are also comfortable, have free wifi, clean bathrooms, reasonable food options and they're consistent.