Like-for-like sales at the 38 Burger King restaurants run by Gowrings were down by 2% during 2000.
Gowrings operates 27 Burger Kings in the South and South-west of England and 11 in the Midlands. It warned in August that trade during the summer had fallen compared with 1999. An improvement in early September was not sustained.
"The drive-thru restaurants in particular suffered as a result of the fuel crisis," Gowrings said.
Things got worse in November and December, blamed on "poor weather and rail disruption". It also claimed that "media speculation over European beef had a negative influence on demand in the UK".
Gowrings plans to open five Burger Kings this year in Birmingham, Portsmouth, Sutton Coldfield, Havant and Reading.