Infiniti's 2007 update of the G series cars significantly improved the interior accommodations and the control layout. This, along with several other attributes made it our top-rated car in the class. A larger 3.7-liter V6 was added to the coupe for 2008, and the sedan a year later, when a seven-speed automatic transmission was also made standard. We didn't think much of the convertible version that arrived in 2009. A less-costly G25, with a 2.5-liter V6 introduced in 2011, sacrifices a little acceleration, but gets much better fuel economy. The G25 was discontinued in 2013. The sedan was redesigned in 2014 and renamed Q50. The old platform carried on and the sedan was renamed Q40; while coupe and convertible versions were named Q60.