A 5 mile commute makes it tough to get excellent mileage. Your Prius should be warm after only a mile or so. They really do warm up quickly. Try to conserve momentum. Coasting up to lights helps, avoiding full stops also helps. If I approach a red light or stop sign, I lightly brake until I'm on battery. I also brake earlier, trying both to let the light turn green, and to avoid hard braking at the last moment. Check your tire pressures. Prius drivers have found 42 front, 40 rear to improve tire life, handling and mpg.