I commute 70 miles one way 5 days a week. Which car is best for me in terms of gas mileage and reliability?

One of your best bets with maximum fuel economy and overall relaibilty in mind would be the Toyota Prius at 50mpg..check out this information: http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=33324

If you are not keen on Hybrids, my Corolla gets 38 to 40 mpg, and you can get in to a 2006 or 2007 for about $11,000 ...If you look at Corollas avoid any newer than 2011 model year, the new ones, 2012 and up, are inferior to those. And on the subject of reliability, it simply can't be beat. There are lots of good cars. This is personal experience and opinion

If it's in your budget and you want more power...take a look at the Camrys. They are a bit more luxurious and can be had with a V6, sacrificing economy but a higher end car

Depending on wether you are searching for new or used, please take a moment to research the J.D. Power and Associates rankings on gas mileage, safety and reliability. Chevrolet and GMC are in the top 5! Surpassing Nissan, Ford, Dodge, Subaru, Jeep, Chrysler, Toyota, Kia, Honda and Acura. Currently there are great incentives out there for cash and financing buyers and even some great deals on pre-owned. GM Certified offers a maintenance program for 2 years/12,000 and a 12 month/12,000 miles full manufacturer warranty. (Now THERE IS PEACE OF MIND! I am not sure where you are located or what the terrain is like where you commute, but the Chevy Cruze is a perfect sedan with great gas mileage and excellent safety ratings as well as the Chevy Equinox (if you are interested in an SUV).