Autoblog and Yahoo may earn commission from links in this article.Infiniti's Forgotten Muscle SedanDo Japanese muscle cars even exist? Sports cars and grand tourers, for sure, but it's hard to pin down any model from Japan that can be classified as such. There is, however, one that we think nearly fits the bill. That would be the short-lived Infiniti M45 from 2003 to 2004.Sure, it was a sedan, but there's just something about it that makes it interesting and amusing. While it wasn't Japan's first V8-powered rear-drive luxury sedan, the title of muscle car seems to wear it well, as it had an engine where it didn't belong in the first place. Still, only enthusiasts seem to remember this car, but we say it's the original M45's time to shine.InfinitiHumble OriginsThe 2003 Infiniti M45 traces its origins to the Nissan Cedric and Gloria. Those nameplates came about as far back as 1959, and the latter was badged as a Prince before Nissan absorbed that brand. It was the kind of car that Japanese salarymen bought, the same way the middle classes in America drove home a Chevrolet Impala, Ford Galaxie, or Plymouth Fury.AdvertisementAdvertisementOver the years and through several generations, the Cedric was the archetypal big sedan (by Japanese standards) that was popular among fleets, taxi agencies, police forces, and middle management. The Gloria, on the other hand, had a sportier twist with unique styling touches. That remained true for the tenth-gen Cedric and eleventh-gen Gloria. The thing is, the biggest engine those otherwise docile sedans got was a 3.0-liter V6 turbo with 276 hp.NissanFilling a GapIn the early 2000s, Infiniti had a gap in its model lineup. The G35 served the compact executive market, facing off against the likes of the Audi A4 and BMW 3 Series. Meanwhile, the Q45 was the brand's challenger to the Mercedes-Benz S-Class and Lexus LS. There was nothing in between, and that 5 Series-sized hole needed to bridge the gap between those two cars. Besides, Lexus had the GS for the longest time, and Infiniti had no answer for that.Conveniently, Nissan had a GS-sized car in its Japanese lineup in the form of the Cedric and Gloria. However, selling those cars as is in the U.S simply wasn't going to cut it. Perhaps in Infiniti's minds, it needed to make a statement the moment it entered the midsize luxury sedan market, and the solution was V8 power.InfinitiEnter the M45Infiniti chose the Gloria over the Cedric for its midsize sedan, but that was the easy part. The car somehow needed to fit a large engine and be federalized to make it U.S.-compliant. Rather conveniently, however, the Gloria's underpinnings were shared with the Q45, meaning the Infiniti M45 engine could be the 4.5-liter V8 from the flagship sedan. The platform was also engineered for left-hand drive, almost as if the Gloria was destined to make its trip to the U.S.AdvertisementAdvertisementThe Infiniti M45 V8 engine made exactly the same power as the one used in the Q45. That meant 340 hp and 333 lb-ft of torque, which was more than what the Lexus GS 400 could offer at the time. It was then mated to a five-speed automatic transmission, also inherited from its larger sibling.For the interior, the Gloria was never meant to be sold in left-hand drive markets. Designing an all-new dash would've been costly, so the end result was the Q45's dash being used instead. As for the exterior, it looked the same as the JDM Gloria save for a few tweaks. There's the Infiniti badge in place of Nissan, a different front bumper, DOT side markers, and the 'Altezza-style' taillights were made to look more conventional.InfinitiAnd the Reviews Were......Pretty average, if we're being honest. Looking at contemporary reviews, you get the impression that it's likable, but not up to par with Audi, BMW, Mercedes, or even Lexus. The car didn't have any major vices, but the Gloria on which the M45 was based was already a four-year-old model by 2003. It also didn't help that the Gloria was never meant to take on Germans in the first place, so sporty reflexes simply weren't there.However, if there's one thing that reviewers were unanimous about, it was the performance. 340 hp was a lot back in the early 2000s, and its 0 to 60 mph sprint under 6 seconds was a huge deal. Despite the restrictive automatic, there was a whole lot of praise about the powertrain. With a starting price of $42,895, it offered a lot of punch for the money compared to its peers.InfinitiThe M45 TodayInfiniti only sold 8,067 units of the original M45 for the 2003 and 2004 model years, so there isn't a lot to choose from today. However, supply was limited in the first place, as the car that would end up replacing both the Cedric and Gloria was still a few years away. That car later became the Nissan Fuga, which became the Infiniti M35 and (second-gen) M45 in 2006. The Fuga-based Infiniti Ms that replaced the Cedric/Gloria-derived models were genuinely good luxury sedans, occasionally beating the Germans and Lexus in comparison tests back in the day.AdvertisementAdvertisementToday, the original M45 is a bit of a cult classic. It has a small but dedicated fanbase that's determined to keep these cars on the road and tirelessly tell its story. While reviews weren't exactly sparkling, its background and creation were surely interesting. The car was a soft-riding, rear-drive V8 bruiser, which in our book makes it more American than many other American sedans at the time.It's also one of the few times America got a JDM 'salaryman' mobile, with the last one being the Toyota Cressida, known as the Mark II in its home market. Sure, the V8 was never offered in Japan, but the M45 is an interesting slice of Japan that was briefly offered stateside.InfinitiNissanView the 8 images of this gallery on the original articleThis story was originally published by Autoblog on Aug 3, 2026, where it first appeared in the Features section. Add Autoblog as a Preferred Source by clicking here.