Increasing levels of traffic congestion are hitting the competitiveness of the West Midlands, transport chiefs have warned.
But transport spending in London is more than 260 per cent what it is in the West Midlands - and the gap is getting larger.
The news follows a Government warning that journey times are set to increase as roads in the region become increasingly busy.
Walsall councillor Coun Gary Clarke, chairman of West Midlands transport body Centro-PTA, said: "Increasing levels of congestion can damage our regional economy."
He highlighted new Government figures which showed the West Midlands is lagging behind other regions in productivity.
And a new study warned that transport spending across the four English regions of the North-east, Yorkshire and Humber, North-west and West Midlands was £239 per head - compared with £631 per head in London.
The report, published by transport bodies across the country including Centro, said just halving the spending gap would generate £4 billion a year to improve transport networks in the North and the West Midlands.
Coun Clarke said: "We need to persuade Government of the importance of investing in an integrated transport system to keep people and goods on the move - and we need to work together as a region to tackle congestion."
The number of trips on West Midland roads is expected to increase by four per cent over the next five years.
But a separate report from the Department of Trade and Industry warned the amount of traffic on West Midland roads was already increasing by above average - and vehicle speeds were falling.
Cars and lorries caught up in West Midlands jams are now travelling almost six per cent slower, according to a DTI survey of competitiveness of the regions.
The statistics are for the wider West Midlands region, including the Shire counties, and show about three-quarters of people travel to work by car. Public transport use is much higher in the major conurbation, and a majority of commuters in Birmingham use the bus, train and Midland Metro to get to work.
The average speed on West Midland roads is 49 mph, lower than anywhere except for London. Road speeds in the region are falling, while in the UK as a whole the average speed has increased.
Meanwhile, the economy is f alling further behind, according to the DTI.
Gross Value Added - the measurement which has replaced GDP as the official assessment of output - was £15.325 per head for the West Midlands in 2004. But the UK average was £16,802, while in London it was £24,955.
The East Midlands, Southwest, East of England and South-east all have higher outputs per head than the West Midlands.
Lower output is echoed in lower pay. Median full-time hourly earnings in the West Midlands are £9.88, below the UK average of £10.56.
Research by the House of Commons published last month found that three of the four constituencies with the worst unemployment rate in the country were in Birmingham.
Ladywood has the highest unemployment rate in the country, at 20.3 per cent, and Sparkbrook and Small Heath was second, with an unemployment rate of 15 per cent.
Hodge Hill has the fourth worst at 12 per cent.