Here's a suggestion: Ask your friends to give you an estimate of what they spend on driving in a month. Average your responses. Take that amount of money from your income, and put it in the bank. In 6 months, tell your friends how much money you have in the bank. Ask them whether they'd rather have that amount in the bank, or drive their cars.
I wish it was possible for me, but having kids, and life in general in the 'burbs makes it not possible. I use my bike when I can. If my wife and I could do without...*runs off to do some math*...we could save about $10k a year. I think I'll be ill.
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Tom
"It hurts so good..."