UNCLE SAM SAYS: "Slow down or I'll have to allow drilling for oil in another pristine wilderness." CHILI SAYS "Ride a bike and defy economics!"

I was asked a few days ago about the most fuel-efficient speed at which to drive your car. I guess I pontificated on this subject in the past. On a normal day many of the things I say can't be trusted, but the always helpful US government offers the Tips to improve your Gas Mileage page. Lucky for me it indicates that 55mph or so is the most fuel efficient speed at which to travel (lucky because that's the number I had spouted out). What's more interesting is that the graph was made in Microsoft Excel and there are no indications as to how old the data are, who collected it, how, or from what vehicles. Wouldn't you think they would have something a bit more advanced? It's the government, after all.
So, being an avid cyclist and having some time on my hands I made a little MathCAD program that investigates things like fuel economy, gasoline prices, relative likes/dislikes for biking and cars and stuff. Here's one outcome chart. Instructions are below:

To interpret the graph,

1. Find the type of biker that you most closely resemble (commuter, avgbiker, or lovescar). Commuters ride all year, even in the snow and cold. Average bikers put their bikes away when it gets cold, but will ride in the rain if necessary. People who love their cars ride only when the sun is out and it's warm.
2. Next, estimate your discount rate for driving a car. This is all driving, in all travel conditions, including traffic. A discount rate of zero means that you love to be in your car more than anywhere else on Earth. A discount rate of 1 means that you would rather be anywhere else on Earth than in a car.
3. Having identified your car discount rate (p.car), move across the x-axis until you reach that value, then move upwards to the line that matches your cycling preference. The corresponding y-value is the price that gasoline will have to reach for you to be indifferent between biking and driving.

NOTE: The parameters can be adjusted for your fuel efficiency, local weather, maintenance costs, and wages. My driving discount rate is around 0.9 and I'm a commuter. Looks like I'm already switched over to biking! I wonder what people think about this. (You can reserve your comments about my relative amount of free time because this is for a class research project about bike path impacts on nearby property values.) From this analysis it looks like it's going to take a lot more than high gas prices to get people to ride their bikes to work! The thing about models like this is that they're just too simple. I don't ride my bike because gas is expensive, I ride it because I love to ride it and I hate riding in cars. Still, it might be interesting to someone else, so I post it here.
How much to you love your car? Here's a dollar value. Find that price of gas at which you are indifferent between biking and driving. You might be surprised at how high it is! Remember that the y-axis is a log scale.