1. Hard to know. There is some minimal slip in an automatic transmission, but check it out and let us know what RPMS the tach says you are going when the speedometer says 70 mph, and then other AWD users can chime in to compare, and we can even try math.2. If the sign was accurate at 77 and the speedo was wrong at 70, then the odometer would be incrementing too slowly, say 10 %. That would mean that your 36,000 mile warranty would actually be good for almost 40,000 real miles. It would also mean that instead of 29.8 mpg, you got closer to 32.8.3. You can call the dealer and see what they have to say. I do not think that there are any dealer calibratable adjustments to the speedometer, and if it is possible, it would take a jig the dealer won't have. But a phone call is free.4. the 2005 AWD is rated at 26 city/31 hwy. Guess it depends on how and where you drive, but 30 would not be unrealistic.You may want to check the air pressure in your tires. Some people have gotten Vibes with overinflated tires, and that would make the tires bigger, which would mean fewer rotations per mile, which would make the speedometer read lower than actual. Not sure what pressure would be required to make a 10% difference though.Charlie's pic from
http://forums.genvibe.com/zerothread?id=6367