MSX ST3 D40

The ST3 D40 is a compact sedan produced by MSX between 2007 and 2013.

Development
The D40 was known for being the only ST3 to feature a longitudinally mounted engine. This layout was a result of MSX insisting on producing only one compact car platform, a move which saw the D40 ST3 and

C40

ST2 share a platform. Rear wheel drive had become a major part of the ST2's character and so the US based team responsible for the ST3 were forced to share development of the longitudinal CML platform.

In order to satisfy the demands of both ST2 buyers looking for a car with sporty dynamics with those of ST3 buyers wanting FWD or AWD for snow, the two cars shared a four-wheel double wishbone suspension setup and a rear subframe, but the front subfames and floorpans were different. While both cars had the same front suspension pickup points, the ST3's engine and firewall were moved forward, so that the engine sat ahead of the front axle similar to an Audi or Subaru, where it was paired with a transaxle gearbox providing drive to the front wheels. The front differential sat below the front of the gearbox in one housing. A front wheel drive prototype was built, but rejected for production by MSX head office due to lacklutsre nose heavy handling, so for the first time, all ST3s were all wheel drive, with a transfer case was mounted at the rear of the transaxle.

The D40 also discontinued the compact 2.5L inline 6 introduced in the transverse engined D30, in favour of an all four cylinder lineup.

Performance
The D40 was the final application of the US built MSX NA4 engine, which traces it's roots back to the orginal D10 ST3. It was offered in both 2.0 and 2.4L variants with either a six speed manual or five or six speed auto. The platform's inability to accept a six cylinder engine meant that the D40 GS had to make do with the 2.4L four cylinder and couldn't match the fastest D30 variants, particularly the final SB4-powered GS 1.6 Turbo, and rumours of a return of the turbo SB4 to replace the NA4 engine.

In 2009, the NA4 was replaced by more compact turbocharged SB4 engines and the automatic transmissions with DCTs. This greatly imporved not only the performance and economy, but also the handling of the nose heavy D40. ST3 engineers passed on the 1.4 used in the base model ST2 and installed the 1.6 litre in the LX, LS and LSE instead, with the GS getting the 2.0L.