The Infiniti G37 was very popular, so why doesn't Infiniti make it anymore? Good news! The 3.5 liter Infiniti G35 became the 3.7 liter Infiniti G37 for model year 2009. With a bigger engine, you'd expect more horsepower and lower gas mileage, right? Well, yes and no. The 2009 Infiniti G37 boasts 328 horsepower, an increase of 22 over the G35. But gas mileage has actually improved a little. The seven-speed automatic G37 gets 1-2 miles more per gallon than its predecessor!