Toyota sienna Toyota siennaThe Toyota Sienna is a minivan that was introduced in 1998 to replace the Previa. There have been two generations of the Sienna. The first generation ended in 2003. During this generation, the Sienna was a 3 or 4-door minivan with a 3.0 liter V6 engine and a 4-speed automatic transmission. The current generation of the Sienna is a 4-door minivan with a 3.3 or 3.5