The San Diego MTS bus system is a public transport bus service serving San Diego County, California. It is part of the San Diego Metropolitan Transit System (MTS). The system operates 97 bus routes in San Diego and the rest of the southern half of the county.^[1][2] There are 85 "MTS Bus" fixed-route services, 9 "Rapid" bus rapid transit routes, and the "MTS Access" paratransit service.

Routes are operated by private contractors and by the San Diego Transit Corporation (SDTC), a subsidiary of MTS. SDTC operates 27 routes based out of downtown San Diego (Imperial Avenue Division), Transdev operates 73 routes based out of Chula Vista (South Bay Division) and El Cajon (East County Division), and operates the "MTS Access" paratransit service that are operated with mini-buses based out of Kearny Mesa (Copley Park Division).

All buses and division facilities, even those used by contractors, are owned by MTS. MTS serves San Diego proper and the surrounding East County and South Bay regions,^[3] while the North County area is served by the North County Transit District (NCTD)'s BREEZE bus system.^[4]

Make/Model	Fleet Numbers	Thumbnail	Year	Divisions	Notes
ElDorado National AeroElite	3001–3006		2014	Copley Park	These are the cutaway buses.
	3101–3131		2016	Copley Park
Gillig Low Floor CNG 40	201–223		2015	Kearny Mesa
	801–826		2013	Imperial Avenue
	901–912		2014	Kearny Mesa
	1401–1410		2017	Kearny Mesa	These buses were repainted into the MTS Rapid livery in 2023, replacing the 300-series New Flyer C40LF buses.
	1701–1738		2020–2021	Kearny Mesa, Imperial Avenue	1701–1722 are the 2020 models, 1723–1738 are the 2021 models.
	2001–2014		2015	South Bay
	2101–2136		2017	South Bay
	2201–2238		2022	South Bay	These are the final Gillig buses delivered to MTS.
	2301–2324		2013	East County, South Bay	2301-2306 transferred to the East County division in 2023.
	2401–2438		2014-2015	South Bay	2401-2418 are the 2014 models, 2419-2438 are the 2015 models.
	2601–2632		2021	South Bay
	2781–2787		2018	South Bay	These buses are exclusively used on route 992. All buses are equipped with luggage racks.
	2791–2795		2021	South Bay
	8201–8213		2015	East County
	8301–8338		2016	East County
	8351–8356		2019	East County
Gillig Low Floor Plus EV 40'	1601–1602		2020	Imperial Avenue
	1603–1607		2021	Imperial Avenue	These buses are painted red instead of green.
MCI D4500CT CNG	8531–8554		2020	East County	These buses are painted in the MTS Rapid Express livery, and are exclusively used on Rapid routes 280 & 290.
New Flyer C40LFR	601–621		2011	Imperial Avenue	622-626 transferred to the South Bay division in 2022, and were re-numbered to 2923-2927.
	701–731		2012	Imperial Avenue
	2901–2927		2011-2012	South Bay	2923-2927 are the 2011 models, and were originally numbered 622–626. 2901-2922 are the 2012 models.
New Flyer XE40	1501–1506		2019	East County, Kearny Mesa, South Bay
New Flyer XE60	7551–7562		2023	South Bay	These buses are exclusively used for Rapid route 227.
New Flyer XN60	1101–1129		2013	Kearny Mesa	These are the first MTS Rapid buses in the MTS fleet, and are primarily used for Rapid route 235. These buses are currently being retired. 10 buses were sold to Santa Cruz METRO from 2023-2024.
	1201–1218		2013	Kearny Mesa, Imperial Avenue	These MTS Rapid buses are primarily used for Rapid route 215.
	1301–1313		2015	Kearny Mesa	These buses are painted in the standard MTS livery, but are regularly assigned to Rapid routes.
	1801–1826		2021	Imperial Avenue	These buses are painted in the standard MTS livery. They're primarily used on routes 7, 10 & 13. These buses replaced the 1000-series NABI BRT-CNG buses in 2021.
	1901–1924		2023	Kearny Mesa	These MTS Rapid buses are primarily used for Rapid routes 201, 202 & 235. These buses are currently replacing the 1100-series New Flyer XN60 buses.
	7401–7410		2017	South Bay	These buses are painted in the standard MTS livery, and are primarily used on route 929.
	7501–7517		2017–2018	South Bay	These MTS Rapid buses are primarily used for Rapid route 225, but they're occasionally seen on Rapid route 227.

• MTS bus routes and schedules
• NCTD bus routes and schedules