When Infiniti dropped a smaller 2.5-liter engine into its entry-level luxury sport sedan for the 2011 and 2012 model years, buyers faced an immediate dilemma. The Infiniti G25 was designed to capture a more efficient, lower-priced tier of entry compared to the dominant G37, but it shared nearly all its sheet metal, interior layout, and chassis tuning with its bigger brother. If you're looking at the used market today, understanding how these two machines stack up against each other reveals whether the smaller displacement engine makes financial sense or leaves you wanting more power.
The primary difference between the two models lies squarely under the hood. The Infiniti G25 features the 2.5-liter VQ25HR V6 engine pushing out 218 horsepower and 187 lb-ft of torque, mated to a seven-speed automatic transmission. Meanwhile, the G37 packs the legendary 3.7-liter VQ37VHR churning out 328 horsepower and 269 lb-ft of torque. Both cars share the FM platform, double-wishbone front suspension, and multi-link rear setup, meaning their road-holding manners are nearly identical on paper, yet they deliver vastly different driving experiences.
Engine Architecture and Performance Output
Examining the powertrain specifics clarifies why these two sedans feel so different in real-world driving. The VQ25HR in the G25 is a smooth-revving, high-compression V6, but it lacks the Variable Valve Event and Lift (VVEL) system found on the larger VQ37. Without VVEL and a full 1.2 liters of extra displacement, the G25 has to work much harder to move a chassis that weighs nearly the same as the G37.
- Infiniti G25 Power: 218 horsepower at 6,400 rpm; 187 lb-ft of torque at 4,800 rpm.
- Infiniti G37 Power: 328 horsepower at 7,000 rpm; 269 lb-ft of torque at 5,200 rpm.
- Power-to-Weight Reality: The G25 yields roughly 0.058 horsepower per pound, whereas the G37 jumps past 0.086 horsepower per pound, creating a stark contrast in acceleration and passing confidence.
On the highway, the G25 requires heavy throttle input to execute quick passing maneuvers. The engine loves to rev, but the torque curve peaks high in the RPM range. Conversely, the G37 delivers effortless acceleration from a light roll, pulling hard across the tachometer without making the driver wait for the transmission to hunt down gears.
Fuel Economy and Daily Driving Realities
One of the main justifications for choosing a smaller engine is fuel efficiency. However, because the G25 pulls a heavy luxury sedan chassis that weighs over 3,700 pounds, the efficiency gains are surprisingly minimal.
According to the U.S. Department of Energy Fuel Economy Guide, the rear-wheel-drive G25 is rated at roughly 20 mpg city and 29 mpg highway. The G37 sits close behind at 19 mpg city and 27 mpg highway. In real-world commuting, many owners report getting nearly identical fuel mileage between the two variants because the G25 driver must keep the throttle pinned further down just to keep pace with modern traffic.
For routine city driving, some drivers actually praise the G25 for a light, willing throttle tip-in and a balanced front end. Because the 2.5-liter block removes a minor amount of weight off the front axle compared to the 3.7-liter variant, turn-in can feel slightly nimble. However, this minor handling nuance rarely outweighs the massive power deficit for driving enthusiasts.
Trim Levels, Equipment, and Market Value
Infiniti kept packaging simple for the G25, offering it in base, Journey, and x (all-wheel-drive) trims. Standard features mirror the G37 Journey trim closely, including leather appointed seating, automatic climate control, and standard luxury amenities. You won't find many stripped-down cloth interiors here.
- G25 Base: Equipped with 17-inch alloy wheels, automatic headlights, and basic audio.
- G25 Journey: Added heated front seats, dual-zone climate control, and a rearview camera.
- G25x: Integrated Infiniti's ATTESA E-TS all-torque-split AWD system for foul-weather traction.
On the used market, the G25 often trades at a discount compared to a comparable G37. Because demand for the higher-output VQ37 engine dominates enthusiast circles, you can occasionally find a clean G25 at a lower price point. If you prioritize reliability, comfort, and interior design over raw speed, that price gap might catch your eye. You can research vehicle history benchmarks directly through the National Highway Traffic Safety Administration to check safety recalls and past performance ratings.
Common Issues and Maintenance Comparison
Both cars benefit from Nissan's robust engineering heritage during this era, but they carry distinct maintenance considerations.
- Gallery Gaskets: While the G37 is well known for potential inner timing cover oil gallery gasket degradation on pre-2012 models, the G25 engine architecture experiences this issue less frequently due to lower thermal and mechanical stress, though high-mileage examples still require scrutiny.
- Transmission Reliability: Both models utilize the RE7R01A 7-speed automatic transmission. Initial model years suffered from harsh shifting and software lag, which typically required dealer firmware updates like ITB12-027 to smooth out part-throttle shifts.
- Parts Availability: Routine filters, brakes, and suspension components are widely shared with the G37. However, specific engine sensors, exhaust components, and intake parts for the rare VQ25HR can be slightly harder to source quickly than the ubiquitous 3.7-liter parts.
Frequently Asked Questions
Is the Infiniti G25 slow compared to the G37?
Yes. The G25 takes roughly 7.5 to 8 seconds to reach 60 mph, whereas the G37 accomplishes the same sprint in about 5.2 to 5.5 seconds. The difference in passing power at highway speeds is even more pronounced.
Do the G25 and G37 share the same body and interior?
They are nearly identical. Aside from minor badge differences on the rear decklid, you cannot tell a G25 and a G37 apart from the outside or inside. They share the same body panels, suspension architecture, and cabin layout.
Why was the Infiniti G25 discontinued so quickly?
Infiniti produced the G25 for only two model years (2011 and 2012) because buyers overwhelmingly preferred the G37. The marginal fuel economy improvement did not justify the heavy drop in horsepower for a luxury sport sedan buyer.
Can you modify a G25 to make G37 power?
Adding power to the VQ25HR is notoriously difficult and expensive. Because it is naturally aspirated and lacks aftermarket support for forced induction kits tailored to this specific displacement, spending money on bolt-ons yields minimal horsepower gains. If you want speed, starting with a G37 is always the smarter path.
