A wealthy businessman has submitted plans for a third runway at Heathrow which he says would be £5bn cheaper than the airport's current scheme.
Hotel tycoon Surinder Arora has put his proposal to the government's public consultation on Heathrow.
Ministers have expressed a preference for the airport's plans for a new runway and terminal costing £17.5bn.
Heathrow said it was already considering some of the ideas, and wanted to lower the cost too.
Arora Group's proposals include changing the design of terminal buildings and taxiways, and reducing the amount of land it is built on.
Mr Arora said: "We want passengers to be at the heart of our plans and the current monopoly at Heathrow, which over-charges airlines and in turn raises fares for passengers, is not the right model for the future.
"Heathrow needs competition and innovation which puts passengers and airlines at the heart of the expansion project."
He added: "One of the options we have proposed to government includes a possible shift of the runway so that it does not impact on the M25 and M4, as we know the M25 junction being affected threatens the deliverability of the whole project.
"We appreciate this is a politically sensitive issue but it is merely an option with additional savings of £1.5bn, whereas the rest of our proposals save up to £5.2bn without the need to amend the runway location."
Willie Walsh, chief executive of British Airways' owner IAG, welcomed the proposals.
He said: "The government should look closely at Arora's proposal as it would significantly reduce costs."
British Airways is Heathrow's biggest customer.
An airport spokeswoman said: "Heathrow's expansion proposals are supported by the government and have widespread cross-party political, business and union support.
"We continue to develop our plans to improve passenger experience, reduce the impact on local communities and lower the cost so we deliver expansion at close to current charges.
"Some of the options we are looking at sound similar to those suggested in this submission, and we will welcome views on these in the public consultation later this year."
Construction will not begin for at least three years, and it could be delayed by legal challenges over the runway's environmental impact.
A Department for Transport spokesperson said: "The government has made clear that it believes a new north-west runway at Heathrow is the best scheme to deliver the economic and connectivity benefits this country needs.
"New capacity will increase competition between airlines resulting in lower fares for passengers.
"A consultation on a draft airports national policy statement closed on 25 May and we are currently analysing the responses, and will set out our next steps in due course."
The Department for Transport has estimated a new runway at Heathrow would bring economic benefits to passengers and the wider economy worth up to £61bn, and create as many as 77,000 additional local jobs over the next 14 years.