Cars to become lighter

An executive from vauxhall stated here on in that car sizes are not going to get any larger,cars across the spectrum are more or less fixed in size.the reason for this is that nanufactures are under pressure to reduce co2  and to make vehicles more fuel efficient.to do this cars cannot become any bigger and heavierfor this reason cars must become lighter and smaller.if the emmisions donot drop the financial penalties for legilaters will be a certainty.