The Mazda Xedos 6 was a European-market luxury car based on the Mazda CA platform also used by the Mazda Capella

Mazda Capella

The second generation rear-wheel drive Capella was available between 1978 and 1982, in both sedan and coupe forms. It was known on export markets as the Mazda 626, with the exception of the United Kingdom, where it was called the Mazda Montrose, the name was changed to honour the local Mazda...

. Identical to the Japan-market Eunos 500

Eunos 500

The Eunos 500 was a luxury car from Mazda's Eunos marque. The 500 was first shown to the public at the 1991 Tokyo Motor Show, and Japanest launch followed soon in early 1992....

, it was produced for model years 1993 through 1999 and was available in two versions, the 1.6i and 2.0 V6.

Despite the very similar appearance to the American market Mazda Millenia

Mazda Millenia

The Mazda Millenia is an automobile which was manufactured by Mazda in Japan from 1993 to 2003.The Millenia was originally planned as the second of three models for Mazda’s proposed luxury brand Amati...

, the Xedos 6 and its Japanese cousin Eunos 500

Eunos 500

The Eunos 500 was a luxury car from Mazda's Eunos marque. The 500 was first shown to the public at the 1991 Tokyo Motor Show, and Japanest launch followed soon in early 1992....

, this vehicle was not sold in the USA market.

The 1.6i was powered by Mazda's 1.6 L DOHC I4

Straight-4

The inline-four engine or straight-four engine is an internal combustion engine with all four cylinders mounted in a straight line, or plane along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft....

 producing 113 and later 107 hp. The 2.0 V6 used Mazda's 2.0 L KF11 and KF56 V6 and produced 144 and later 140 hp. Mazda Eunos 500 was powered by 160 hp KF-ZE engine.

Production of the 2.0 V6 began on May 1, 1992 and lasted through January, 1999. The 1.6i started on August 1, 1993 and ended on August 1, 1998. Totally produced 72101 Xedos 6 (Eunos 500) vehicles.
Engines:

• 1.6 L B6-9,B6-E DOHC I4
  Straight-4
  The inline-four engine or straight-four engine is an internal combustion engine with all four cylinders mounted in a straight line, or plane along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft....
  
  
• 2.0 L KF-1 DOHC V6

The Xedos 6 platform was derived from the Mazda 626

Mazda 626

The Mazda 626 is an automobile that was produced by Mazda for the export market. It was based on the Japan-market Mazda Capella. The 626 replaced the 616/618 and RX-2 in 1979 and was sold through 2002, when the new Mazda6 took over as Mazda's large family car...

 sedan which also formed the basis of the Mazda MX-6

Mazda MX-6

The first generation MX-6 appeared in 1988 and lasted until 1992 in the United States. In some markets the model years were from 1987 to 1991. It was based on a series of futuristic sports compact concept cars of the early 1980s...

.
Also this platform has Mazda Efini (MS-8), Capella, Japan cousin of 626 GE (1991–1997) and also Ford Probe

Ford Probe

The Ford Probe was a coupé based on the Mazda GD platform, and powered by a 2.2 L SOHC 4 cylinder Mazda F2 engine.The first generation Probe appeared in 1988 and lasted until 1992 in the United States. In some markets the model years were from 1987 to 1991...

- II.
Most of their parts (engine, transmission, brakes, steering and suspension) are unified.