| Who are the people behind the cars? |
| The Works Teams |
 | | Team Honda | Honda Civic Type-R | Arena International continues with the Civic Type-R in 2004, starting the season with one entry. |
 | | Seat Sport UK | Seat Toledo Cupra | Spanish marque Seat makes its BTCC debut in 2004 with a pair of ETCC spec Toledo Cupras. |
 | | Team Petronas Syntium Proton | Proton Impian | A redeveloped car and a new driver line up for the Malaysian marque in 2004. |
 | | Vauxhall Racing | Vauxhall Astra Coupe | Having evaluated the Vectra over the winter the Triple Eight Race Engineering team continues to run Astra Coupés on behalf of Vauxhall. |
| The Independent Teams |
 | | Collard Racing | Vauxhall Astra Coupe | Rob Collard's team move up to the Touring class with an Astra Coupe for 2003. |
 | | Edenbridge Racing | BMW 320i | Edenbridge runs a sole ETCC-spec BMW 320i in 2004. |
 | | Kartworld Racing | MG ZS | After running a limited programme last year, Kartworld Racing enters an independent MG ZS in 2004. |
 | | Mardi Gras Motorsport | Honda Civic Type-R | Mardi Gras enters new-era BTCC for the first time this year, running a unique gas-powered ETCC-spec Honda Civic Type-R. |
 | | Synchro Motorsport | Honda Civic Type-R | Having just missed out on the Independents cup last year, Synchro Motorsport returns for another attempt with their Civic Type-R |
 | | Team Dynamics | Honda Civic Type-R Matt Neal returns to his independent roots as Team Dynamics enter a pair of Civic Type-Rs. |
 | | Team Sureterm | Vauxhall Astra Coupe | Alfa Romeo 156 | GA Motorsports runs two Astra Coupés and an ETCC spec Alfa Romeo 156 under the 'Team Sureterm' banner in 2004. |
 | | VX Racing Jr | Vauxhall Astra Coupe | A return to the series for Tech-Speed, running a single Astra Coupé. |
 | | West Surrey Racing | MG ZS | Running as independents in 2004, West Surrey Racing continues with the MG ZS. |