June saw UK new car registrations rise 6.2% to 228,291 units.
There were 1,287,265 new cars registered in first six months of the year – a 10.6% rise and the best half-year total since 2005.
The Society of Motor Manufacturers and Traders said consumer demand for efficiency has driven alternatively-fuelled vehicle registrations up 51.3% to 23,337 units year-to-date.
The UK's new car market is on track for 2.4 million new car registrations in 2014, up more than 6% on last year.
Mike Hawes, SMMT chief executive, said, "Improving economic conditions have helped propel the UK new car market to a strong first half-year performance, with registrations up 10.6% on the same period in 2013.
"Key to attracting consumers is the ever-improving efficiency of new cars, an important factor that is highlighted by the 51.3% increase in alternatively-fuelled vehicle registrations so far this year. The overall market has risen faster than we were expecting but, after a bumper March, growth is showing signs of stabilising around our forecast level."