Aeromexico starts new non-stop B-737 service between Mexico City and Sacramento on April 5th; Mexico City and Ontario California April 6th. 124 passenger seats with 12 in Clase Premier.

I found introductory fares SMF-MEX for $275 r/t in economy and $700 r/t Clase Premier for Mon or Wed departures out of SMF for a few dates in April and May.

Ontario - Mexico City*
Mexico City - Ontario*

AM 0793
1:05 a.m.
7:40 a.m.
Tuesday, Thursday, Fridays and Sunday

AM 0792
9:10 p.m.
11:25 p.m.
Monday, Wednesday, Thursday, and Saturday

Sacramento - Mexico City*
Mexico City - Sacramento*

AM 0791
1:10 a.m.
7:35 a.m.
Monday, Wednesday, and Saturday

AM 0790
8:35 p.m.
11:40 p.m.
Tuesday, Fridays and Sunday