The 1 Series was first offered to the market in 2004 as a five-door hatchback.
The 1 Series is built in Regensburg and Leipzig, Germany, with the 4 cylinder petrol/gas engines coming from the Hams Hall plant in Coleshill north east of Birmingham, England.
During its first full year on the market in 2005, it became one of BMW's most successful products. 149,493 units were sold, leading to a third-place finish in total numbers sold by model. Only the 3 and 5 Series sold better.
2007 mid-generation refresh
BMW upgraded the 1 Series for 2007 and introduced a 3-door sports hatch variant (code named E81). Changes to the model were minor headlight and taillight revisions, new front/rear bumpers and minor revisions to the interior. The dashboard has been updated, and a recommended gear indicator is now present on models with manual transmissions.
New technologies include auto start/stop, Brake Energy Regeneration, Electric Power Steering, an electric water pump, and a host of drivetrain modifications designed for fuel economy, increased performance, and lower emissions. BMW marketing has named this combination of technologies EfficientDynamics, which will also be implemented in other BMW models.
The 1 Series is effectively the first in the world to have mild hybrid technology as standard equipment, although BMW is careful in its marketing not to label it as a hybrid vehicle, as this brings market expectation of electrically assisted drive.
The flagship of the range will be the 135i with a 3-litre twin-turbo petrol engine, generating 225 kW/306 hp (DIN) with its six cylinders. This model also comes with a modified M sports package as standard. The 135i comes with the world's first differential with double-helical ball bearings which have the advantage of running at an even lower operating temperature reached more quickly than before thanks to the reduction of fluid required in the differential . The 123d (150 kW/204 hp(DIN)) heads up the range of diesels and is the first ever 4-cylinder diesel engine to come with sequential twin-turbo technology. In terms of fuel consumption, the 123d and 120d rate between 4.8L/100km (59mpg-imp; 49mpg-US) and 5.2L/100km (54mpg-imp; 45mpg-US).