The transport group, which also runs the c2c rail service in Essex, said "competitive" pricing and faster, more direct services enabled the coach division to post underlying revenues growth of 1% so far this year.
National Express has been hit by the withdrawal of the Government's £16 million senior citizen concession scheme, which meant one million fewer subsidised journeys last year.
The group said coach concession revenues are down 10% this year, which analysts at Espirito Santo called "somewhat concerning".
The operator has responded by slashing prices - including half a million £5 fares - in a challenge to rival Stagecoach's Megabus service.
National Express said coach revenues during Easter were an "encouraging" 6% ahead.
It is hopeful a new contract to run coaches between London Victoria and Luton Airport, more services to Gatwick Airport and the sale of tickets through budget airline Ryanair will give the division a further boost.
The group's bus division, which serves the West Midlands and Dundee, grew underlying revenues 3%. Poor weather squeezed passenger numbers and profits were hurt by a cut in government grants for bus operators.
But National Express said encouraging signs of growth in April, plus rising concession revenues, paint an optimistic outlook for the division.