International Motor Industry Events says this would make attendance 24% up on the Birmingham event in 2004. Official figures will be publicised following an audit.
Rob Mackenzie, IMIE managing director, said: "We were presented with a huge challenge by the motor industry - to organise a successful motor show that befitted the second largest new car market in Europe. We embraced that challenge and hosted the most exciting and well-received motor show in a generation. Plans are already underway to build on this success story and create an even more breathtaking event in 2008."
SMMT chief executive Christopher Macgowan said: "Moving the motor show to London was no small step for the motor industry. But 2006 delivered a giant leap in the show's standing on the international stage. I attribute much of that to imie's hard work in taking up the baton to bring visitors and exhibitors a show for which we can all be truly proud."
The British International Motor Show is organised under license from the SMMT.