I don't understand the problem. Walking and biking are about the same... Which would you prefer?

Are they actually the same? I could not walk .7 and .8 miles in my climate in work clothes and not need to change. I'd end up arriving less sweaty during the warmer months by riding than I would if I walked.

My previous commute was about equal riding vs. driving, primarily due to far-away parking options. I saved $300 yearly on parking and about $4 weekly on gas. My current commute is not equal, riding is about 50% longer than driving, parking included. I now bus on the way in with .4 and 1.2 mile connectors, and ride back 9 miles. The bus lets me not have to shower on arrival.

You could ride back occasionally, if you need to justify the bike.