The TSX and Accord V6 are currently very close in price. As you stated, the fuel economy for both cars are nearly identical (TSX gets +1 in the city, while the Accord gets +1 on the highway), despite the fact that the TSX only has a 2.4L I4 while the Accord has a 3.5L V6 and is bigger.Other differences:Acura offers a longer warranty (both basic and drivetrain) and free roadside assistance.The Accord is more powerful and quicker, but the TSX will handle better.The Accord is larger (interior and exterior).The TSX will have more standard features (e.g. HID, Bluetooth, Sportshift, seat memory)The TSX can be had with a 6-spd MT, while the Accord sedan only comes with an AT.If you do want to get a 2008 TSX, I'd recommend waiting until the fall to get the best pricing, as the 2009 TSX is a new design.
