You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
1973_oil_crisis

Context:
An increase in imported cars into North America forced General Motors, Ford and Chrysler to introduce smaller and fuel-efficient models for domestic sales. The Dodge Omni / Plymouth Horizon from Chrysler, the Ford Fiesta and the Chevrolet Chevette all had four-cylinder engines and room for at least four passengers by the late 1970s. By 1985, the average American vehicle moved 17.4 miles per gallon, compared to 13.5 in 1970. The improvements stayed even though the price of a barrel of oil remained constant at $12 from 1974 to 1979. Sales of large sedans for most makes (except Chrysler products) recovered within two model years of the 1973 crisis. The Cadillac DeVille and Fleetwood, Buick Electra, Oldsmobile 98, Lincoln Continental, Mercury Marquis, and various other luxury oriented sedans became popular again in the mid-1970s. The only full-size models that did not recover were lower price models such as the Chevrolet Bel Air, and Ford Galaxie 500. Slightly smaller, mid-size models such as the Oldsmobile Cutlass, Chevrolet Monte Carlo, Ford Thunderbird and various other models sold well.

Question:
Which full-sized model cars were not popular?

Chevrolet Bel Air