Why the G25 vs G37 comparison comes up so often
The Infiniti G lineup ran from about 2002 to 2013 across two generations, and the G25 is one of those cars people bring up when they're looking at used imports or trying to understand what separated the trims. It's easy to get confused because Infiniti changed the naming scheme depending on the market. The G25 wasn't really a stripped-down G37 in most cases — it was a different engine, a different tune, and in some years a different approach to the whole platform. Here's what I found after spending time with both cars and talking to a bunch of people who've owned them. The G25, in the Japanese domestic market version, used the VK25DET — a 2.5-liter turbocharged V6 that made around 280 horsepower in stock form. That's different from the G35 and G37 which were mostly NA. The G37 sedan in the US got 330 horsepower from the 3.7-liter VK37DE in the earlier years and later the VK37DD with direct injection pushing it to about 332 horsepower. The G37 coupe and sedan were the performance benchmarks for this generation. What matters more than peak horsepower though is how the cars actually drive. The G25 felt different because of the turbo delivery. There's boost coming in around 2,800 RPM and it holds fairly linearly to redline. The G37 is more of a top-end power creature. It pulls hard all the way up but doesn't have that early torque shove. For everyday driving, the G25's turbo character can actually feel more responsive off the line. The G37 wins on open road and highway passing because it has more total power to work with.
I ran into a specific problem when comparing a 2010 G25 Sport with a 2009 G37 sedan that I'd bought for parts. The G25's ATTESA AWD system in the Sport trim was causing a rear differential vibration at about 60 mph. Turned out the rear differential fluid was old and had never been changed — Infiniti's spec says 60,000 miles but that's under ideal conditions. Real-world, especially if the car's been doing a lot of warm-up spins or track use, that fluid breaks down faster. I replaced it with OEM Infiniti ATFE and added a second change at 30,000 miles going forward. The vibration went away completely. This is something a lot of people miss because they look at the AWD system as sealed for life. The transmission difference is another area where these cars diverge. The G37 got the RE5R05A 5-speed automatic as standard and the Jatco 7-speed automatic (the one that also went into the Nissan GT-R) as an option. The G25 in Japan mostly came with the 7-speed auto or a 6-speed manual in the Sport trim. The Jatco 7-speed in the G37 is generally considered more robust than the older 5-speed, but both have known issues if they're not maintained. The 5-speed tends to develop shift flare around 40,000 to 60,000 miles if the fluid was never changed. It's fixable with a proper flush and a valve body rebuild kit, but expect to spend around $800 to $1,200 at a specialist shop. Brakes are another practical consideration. The G37 has significantly larger rotors and a more aggressive brake pad setup than the G25, even in Sport trim. The front rotors on the G37 are 350mm with four-piston calipers. The G25 sits at 330mm with single-piston floats. If you're planning any track use, the G37 brakes will outlast the G25 by a meaningful margin. I've seen G25 brake rotors warp after three track days on a typical street setup. The G37 can usually handle five or six before needing replacement under the same conditions.
Handling characteristics differ too. Both cars share the same basic double-wishbone front and multi-link rear suspension geometry, but the spring rates, damper valving, and anti-roll bar sizing vary between trims. The G37 Sport and Performance packages add stiffer bushings and a more aggressive camber setup. The G25 Sport has some of that same hardware but the lighter turbo engine mass changes the weight distribution enough that the chassis tuning isn't identical. Drivers familiar with the G37 sometimes find the G25 feels slightly more neutral in mid-corner but with less ultimate grip at the limit. One counter-intuitive thing about these cars: the G25's turbocharged engine can actually be more reliable than the G37's NA V6 in the long run if you're looking at high-mileage examples. The G37's VK37 has known issues with timing chain stretch on higher mileage units, especially the direct injection models from 2011 onward. The VCDB (variable cylinder deactivation) system on the DI versions can cause rough idle and check engine lights. The G25's turbo doesn't have VCDB and the timing chain on the VK25 is generally shorter and less prone to the same kind of wear. That doesn't mean the G25 is problem-free — the turbo itself can develop boost leaks at the intercooler piping around 100,000 miles — but it's a different failure mode. If you're trying to decide between the two, here's my practical take. Get the G37 if you want the better performance numbers, the more mature platform with more aftermarket support, and don't mind paying more for maintenance. Get the G25 if you're on a tighter budget, want something that feels quick in city driving, and are comfortable with the import part sourcing. The G25 parts supply is much more limited in North America unless you go through Japanese wrecking yards or specialist importers.
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I've also found that G25 buyers sometimes overlook the importance of verifying whether a particular example is AWD or RWD. The Sport trim comes in both configurations, and the AWD version adds significant weight and complexity. A properly maintained AWD G25 is a capable all-weather car. An AWD G25 with a neglected transfer case is a money pit. Always check the service records for the transfer case fluid and the rear diff fluid specifically. Those are the two items most commonly neglected on imported examples. There's no single winner in this comparison because they're aimed at slightly different buyers. The G37 is the more complete performance sedan. The G25 is the more interesting entry point if you're willing to do the legwork on parts and maintenance. Neither is a perfect car, but both are genuinely good once you understand what they need.
