A NEW diesel-powered SEAT will be Britain's most economical car when it goes on sale in August. Fuel tests show the Ibiza TDI - the only supermini with an electronically-managed, intercooled and turbocharged motor - boasts an extra urban consumption figure of 70.6mpg under the latest test procedure.

Urban economy of the £12,995 hatchback is 40.9mpg and the combined figure is 58.9mpg. Under the previous test formula, Citroen's AX diesel held the UK economy record between 1989 and 1993 with 78.5mpg at a steady 56mph.

SEAT has also unveiled the Ibiza 2.0 8v Cupra Sport which went on sale this week and takes the current line-up of GTi Ibiza models to five. The 123 mph scorcher costs £11,595 on the road and is the only two litre GTi supermini available. Powered by a 115 bhp engine the car has a 0-60 mph time of 9.6 seconds. Also on sale in the UK at the same time is the new range-topping Ibiza 2.0 16v GTi which, in addition to air conditioning and a sunroof can now be had with the option of Recaro front seats at the new price of £15,995 on the road.