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2003 Infiniti M45 Overview, Reviews, Ratings & Specs

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Drew B | October 20, 2025
The 2003 Infiniti M45 was a rear-wheel-drive luxury sedan designed to compete with established German rivals. It was part of the first generation of the M-series, built on the Nissan Y50 platform. Available primarily in one well-equipped trim, it aimed to offer a compelling blend of performance and luxury for its price. Its powerful V8 engine and sophisticated features made it a standout choice for those seeking a premium driving experience without the stratospheric cost of some competitors.
The Good

The 2003 M45 boasts a potent V8 engine delivering exhilarating performance for the enthusiast, while its refined interior and smooth ride offer exceptional comfort for everyday commuting. Its elegant design appeals to emotional desires for luxury, and its strong value proposition, considering its features and performance, satisfies practical buyers. Reliability is generally good, making it a sensible, albeit stylish, choice.

The Bad

Potential buyers of the 2003 Infiniti M45 should be aware of possible issues with the timing chain tensioner, which can lead to noise and eventual failure. Premature wear on brake components and the transmission can also be concerns. Additionally, some owners report issues with the navigation system and electrical components.

2003 Infiniti M45: Quick Overview

  • Engine Options: Only one engine was offered for the 2003 model year: a 4.5-liter V8.
  • Horsepower: The 4.5L V8 engine produced 340 horsepower.
  • Torque: It generated 333 lb-ft of torque.
  • Transmission: A 5-speed automatic transmission was standard.
  • Drivetrain: Rear-wheel drive (RWD) was the only drivetrain option.
  • Fuel Economy: Estimated EPA ratings were around 16 mpg city / 22 mpg highway.
  • 0-60 mph Times: Typically in the mid-5-second range, showcasing its potent performance.
  • Towing Capacity: Not applicable; this vehicle was not designed for towing.
  • Trim-Level Features: The 2003 M45 was essentially offered in one, highly-equipped trim. Standard features often included:
    • Leather upholstery
    • Heated front seats
    • Power-adjustable front seats with driver memory
    • Bose premium audio system
    • Xenon HID headlights
    • Power sunroof
    • Automatic climate control
    • Cruise control
    • Keyless entry
    • Satellite radio capability
    • Optional features could include a navigation system and rear-view camera.

2003 Infiniti M45 Specifications

Vehicle Information
Year 2003
Make Infiniti
Model M45
Trim -
Style Sedan
Type Sedan
Category Mid-Size Car
Manufacturing Details
Made In Japan
Manufacturing City TOCHIGI
Dimensions
Doors 4-Door
Curb Weight 3851 pounds
Gross Vehicle Weight Rating 4830 pounds
Overall Height 57.60 inches
Overall Length 197.20 inches
Overall Width 69.70 inches
Wheelbase Length 110.20 inches
Standard Seating 5
Engine & Performance
Engine 4.5-L V-8 DOHC 32V
Engine Size 4.5L
Engine Cylinders 8
Transmission 5-Speed Automatic
Transmission Type Automatic
Transmission Speeds 5-Speed
Drivetrain Rear-Wheel Drive
Additional Features
Anti-Brake System 4-Wheel ABS
Steering Type Rack & Pinion
Pricing
Manufacturer Suggested Retail Price (MSRP) $42,300
Invoice Price $38,272
Delivery Charges $545

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What Problems Does the 2003 Infiniti M45 Have?

The 2003 Infiniti M45, while generally well-regarded, does have some common issues that owners and potential buyers should be aware of. One of the most frequently cited problems is related to the timing chain tensioner. Over time, these tensioners can wear out, leading to a rattling or ticking noise from the engine, particularly on startup. If left unaddressed, this can lead to significant engine damage. Another area of concern can be the transmission. Some owners have reported issues with rough shifting or premature failure, especially on higher-mileage vehicles. Regular fluid changes are crucial to mitigate this risk.

Brake components, such as rotors and pads, can also experience accelerated wear, which might be more pronounced given the vehicle's performance capabilities. Electrical gremlins are not uncommon in luxury vehicles of this era, and the M45 is no exception. This can include issues with the power windows, door locks, or infotainment system, including the navigation unit, which can become unreliable or cease to function. Some owners have also reported problems with the fuel level sensor and, less frequently, the ABS system. While there haven't been widespread, major recalls specifically targeting the 2003 M45 for critical safety defects, it's always advisable to check for any outstanding recalls with the NHTSA. Long-term reliability is generally considered good if the vehicle has been meticulously maintained, particularly with timely oil changes and attention to the aforementioned common issues.

How long will the 2003 Infiniti M45 last?

The 2003 Infiniti M45, with its robust V8 engine and solid build, is capable of achieving impressive mileage, often exceeding 200,000 miles with diligent care. Many owners report enjoying their vehicles for 10 to 15 years, especially if they adhere to a strict maintenance schedule. The V8 engine itself is known for its durability. However, long-term weaknesses tend to emerge in areas like the timing chain tensioners and the automatic transmission, as these components can be costly to repair. Regular fluid services and prompt attention to any unusual noises or performance changes are critical for maximizing the lifespan and minimizing the impact of these potential weaknesses. Overall, with good maintenance, it offers excellent long-term durability.

What Technology & Safety Features are Included?

The 2003 Infiniti M45 offered a respectable array of technology and safety features for its time, aiming to provide a luxurious and secure experience. Standard tech often included a premium Bose audio system, typically with an in-dash CD player, and satellite radio readiness. Many models came equipped with a navigation system, though its functionality and screen clarity might seem dated by modern standards. Other convenience features usually found were automatic climate control, power-adjustable heated front seats with memory settings for the driver, and keyless entry.

In terms of driver assistance, the 2003 M45 featured standard cruise control and often had a rear-view camera integrated with the navigation system on higher-spec models. While advanced driver-assistance systems (ADAS) like adaptive cruise control or lane-keeping assist were not common for this era, the M45 prioritized core safety.

Safety features included front and side-impact airbags for the front occupants, and side-curtain airbags were often standard or part of an optional package to protect occupants in a side collision. Anti-lock brakes (ABS) and traction control were also standard. Regarding crash-test ratings, the M45 generally performed well for its class during its production run. While specific ratings for the 2003 model year might be less detailed than today's comprehensive testing, its structural integrity and airbag systems contributed to a safe passenger compartment. It's advisable to check official safety reports from organizations like the NHTSA or IIHS for specific performance data if available for this model year, although comprehensive data for older vehicles can be scarce.

What Colors Options are Available?

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2003 Infiniti M45 Prices and Market Value

When new, the 2003 Infiniti M45 had an original MSRP that typically ranged from approximately $48,000 to $52,000, depending on optional packages. As a luxury sedan from the early 2000s, it experienced significant depreciation, as is common for this segment. Today, used 2003 M45 models can be found for anywhere from $3,000 to $8,000, heavily influenced by mileage, condition, and maintenance history. Factors affecting resale value include the presence of the premium sound system, working navigation, and any evidence of consistent maintenance. Vehicles with lower mileage and fewer documented mechanical issues will command higher prices. Major repairs or neglect can severely diminish its market value.

2003 Infiniti M45 Cost of Ownership

Owning a 2003 Infiniti M45 can be moderately costly, especially when considering repairs and maintenance. Insurance premiums will likely be higher than for a mainstream sedan due to its luxury status and V8 engine. Fuel economy is not its strong suit, with the V8 consuming a notable amount of gasoline. Maintenance costs can be average to high; routine services are standard, but specialized Infiniti parts and labor can be pricier. Repair costs are a significant factor, particularly if issues arise with the V8 engine, transmission, or electronics. Therefore, the M45 is generally considered more costly to own than an economy car, requiring a budget that accounts for potentially higher upkeep.

2003 Infiniti M45 Fuel Efficiency

Fuel Type Gasoline
Fuel Capacity 21.10 gallons
City Mileage 17 miles/gallon
Highway Mileage 23 miles/gallon

2003 Infiniti M45 Safety Rating

NHTSA
Side Driver Rating
Frontal Passenger Rating
Rollover Rating
Side Rear Passenger Rating
Frontal Driver Rating
IIHS
Rear Crash Protection/Head Restraint Ratings Not Tested
Moderate Overlap Front Test Results Not Tested
Side Impact Test Results Not Tested

2003 Infiniti M45 Warranty

Basic
Original warranty 48 months / 60,000 miles
Estimated remaining Expired
Powertrain
Original warranty 72 months / 70,000 miles
Estimated remaining Expired
Rust
Original warranty 84 months / unlimited miles
Estimated remaining Expired

2003 Infiniti M45 Insurance

Insurance for a 2003 Infiniti M45 is moderately priced, reflecting its status as a Sedan with strong safety ratings and
reasonable repair costs.

How Does the 2003 Infiniti M45 Compare to Other Sedan?

The 2003 Infiniti M45 entered a competitive luxury sedan segment, facing off against stalwarts like the BMW 5 Series (E60 generation), Mercedes-Benz E-Class (W211), and Lexus GS. In terms of performance, the M45's 340-hp V8 often outgunned its German competitors in base or mid-level trims, offering brisk acceleration that appealed to those prioritizing power. Features-wise, the M45 was well-equipped for its price, often matching or exceeding the standard features of its rivals, particularly concerning its premium audio system and available navigation.

Reliability is where the M45 presented a mixed bag compared to the Lexus GS, which is renowned for its bulletproof dependability. While the M45's V8 is robust, its specific weaknesses, like the timing chain tensioner, can be a concern. The German rivals often faced their own, sometimes more complex, electrical and mechanical issues. Price-wise, the M45 offered a significant value proposition. It typically cost less when new and held its value similarly to its German counterparts, but often provided more V8 power and comparable luxury features for the money than a similarly priced Lexus.

Similar Alternatives:
  • Lexus GS 300/430 (2001-2005): The GS 430 offered similar V8 performance and legendary Lexus reliability, often with a more refined interior. The GS 300 offered a smoother, albeit less powerful, six-cylinder option.
  • Acura RL (2005-2008): While a bit newer, the RL offered all-wheel drive, a strong V6, and a comfortable, tech-laden interior, though typically at a higher price point.
  • Cadillac CTS (2003-2007): The first-generation CTS offered a more American take on the sport sedan, with available V8 power and a distinctive design, though interior quality and refinement were often considered less than the M45.

Potentially Better Alternatives:
  • For ultimate reliability, the Lexus GS series is often a safer bet.
  • For a more engaging driving experience, a BMW 5 Series (E60) with a strong maintenance history could be considered, though potentially more complex and expensive to maintain.

Final Verdict: Is the 2003 Infiniti M45 a Good Sedan?

The 2003 Infiniti M45 is ideal for the budget-conscious enthusiast who desires V8 power, luxury, and a distinctive styling without the exorbitant costs of newer premium sedans. It's an excellent choice for those who prioritize performance and comfort over cutting-edge technology. It is worth buying as a used vehicle, provided it has been meticulously maintained. Buyers should thoroughly inspect for common issues like timing chain tensioner wear and transmission health. Given its age, it's a purchase that requires a willingness to invest in potential repairs to keep its V8 heart beating strong. A pre-purchase inspection by a mechanic familiar with Infiniti vehicles is highly recommended. Focus on lower-mileage examples with a comprehensive service history for the best ownership experience.

2003 Infiniti M45 Owner Reviews

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Drew B

Drew is a seasoned automotive expert and contributor to VinCheck.info. With nearly 15 years of experience as a former Porsche technician, he brings a wealth of hands-on knowledge to his writing. Born in North Carolina, a region renowned for its deep-rooted NASCAR culture, Drew developed a passion for cars early in life, often building and working on vehicles from a young age. At VINCheck, Drew leverages his extensive technical background to provide in-depth analyses of various vehicles. His articles often focus on engine performance, reliability, and maintenance insights, offering readers practical information grounded in real-world experience. Some of his notable contributions include reviews on the Mazda CX-5's longevity and detailed examinations of engine options for models like the 2011 Toyota Camry and Tacoma