SAVING GAS WITH A digital tire gauge? Not a bad idea, I guess, and keeping your tires inflated properly is a good idea anyway, but don’t expect anything really dramatic.
UPDATE: Some readers recommend filling tires with nitrogen. I’m pretty skeptical of this — air is nearly 80% nitrogen anyway, and upping the percentage to something likely to be still well below 100% (because of residual air in tires, etc.) doesn’t seem at all likely to make a difference.