The London Assembly is pressing Philip Hammond to return some of the £500m the capital contributes to the government in vehicle excise duty (VED).
Sadiq Khan has complained that none of the VED generated by London is spent on roads in the capital, which he says has put a strain on Transport for London (TfL), which has cut some of its road maintenance services.
In a letter to Hammond, Gareth Bacon, chair of the Assembly's budget and performance committee, has complained that fewer than 40 of the 4,400 miles of motorways and A-roads managed by Highways England are in London.
"It is unfair that London should be making such a large contribution to the road network in the rest of the country," Bacon said.
"Without funding from VED, TfL is instead using other revenues to maintain and improve its roads. With most of its revenue coming from fares, this means in effect that people using public transport are cross-subsidising the road network.
"Just as it is unfair that Londoners should be making such a large contribution to the national strategic road network, we think it is unfair that public transport passengers should have to cover the costs of the TfL road network."