DETROIT (Reuters) - Ford Motor Co <F.N> said on Tuesday U.S. sales fell 28 percent in June on an unadjusted basis, driven by steep declines in sales of trucks and SUVs under rising gasoline prices.

Ford Motor Co <F.N> said on Tuesday U.S. sales fell 28 percent in June on an unadjusted basis, driven by steep declines in sales of trucks and SUVs under rising gasoline prices.

A lobbying group for 10 major automakers said Tuesday the government is underestimating the cost of increasing fuel economy standards and wants those standards to go into effect too quickly.

General Motors surprised investors with a sales decline that was much less steep than expected, and the company's shares skyrocketed higher.

A last-minute no-interest financing offer and strong sales of some cars helped General Motors Corp. keep its U.S. sales over Toyota Motor Corp. last month, but it was still the worst June for the industry in 17 years and a harbinger of more misery ahead.

Chrysler LLC said Monday it will close one Missouri plant indefinitely this fall and cut production at another due to slumping demand for trucks and other large vehicles.

Shares of General Motors tumbled to a 54-year low while smaller rival Ford Motor hares fell as much as 10 percent on Monday on concerns record oil prices would further hit U.S. demand for vehicles.

By Jui Chakravorty Das

Among the sector activity stories for Monday, June 30, from AP Financial News:

DETROIT (Reuters) - Chrysler LLC <CBS.UL> said it scheduled a briefing on Monday afternoon to discuss an unspecified "manufacturing action" it plans to take in response to a slumping U.S. auto market.

Shares of General Motors tumbled to a 54-year low while smaller rival Ford Motor hares fell as much as 10 percent on Monday on concerns record oil prices would further hit U.S. demand for vehicles.

DETROIT (Reuters) - Shares of General Motors Corp <GM.N> tumbled to a 54-year low while smaller rival Ford Motor Co <F.N> shares fell as much as 10 percent on Monday on concerns record oil prices would further hit U.S. demand for vehicles.

Shares of many auto suppliers tumbled Monday, as both General Motors Corp. and Ford Motor Co. both hit historical lows a day before the release of what's expected to be weak June sales figures.

Shares of General Motors Corp. plunged Wednesday to close below $10 for the first time in more than half a century, on worries about the company's cash needs and speculation about a possible bankruptcy protection filing down the road.

CHICAGO (Reuters) - U.S. truck and engine maker Navistar International Corp <NAVZ.PK> said on Monday the U.S. pickup truck market was in a "stranglehold," squeezed by both economic weakness and high diesel fuel prices.