More information, such as year and engine size, would help in answering your question.
I have a1984 Chevrolet Celebrity V6with carburetter and three speed automatic that gets about 18 mpg on the road, less around town.
I have a 1986 Chevrolet Celebrity V6with multiport fuel injection and automatic overdrive that gets 23 to 24 mpg on the road, less around town.
I have had two other 4 cylinder Chevrolet Celebrities with automatic transmission that both consistently got 30 mpg on the road.
I have yet another 1987 Chevrolet Celebrity with a 1990 3.1 V6 and a 1990 Pontiac 6000 automatic overdrive transmission that gets 30 mpg.
I have a 1997 chevy tahoe, and i get about 10 miles to the gallon usually
5.8 miles per gallon
about 10 miles per gallon
a 1997 Chevy Tahoe gets around 16 miles to the gallon highway and about 10 miles to the gallon around town that's about the best you get out of them.
A 1991 Chevy Suburban will get 11 miles per gallon if driving in the city. It gets around 15 miles per gallon on the highway.
The 1993 Chevy Suburban gets 11 miles per gallon when driving in the city. This model gets 16 miles per gallon on the highway.
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A Chevy Malibu that was made in 1998 will get between 20 and 32 miles per gallon. The car will get around 23 country miles and 32 highway miles per gallon.
The miles per gallon that an El Camino gets depends on the size of the engine. An El Camino with a Chevy 350 gets about 22 miles per gallon.
There is no such thing as a 2005 Chevy Lumina
I have a 99 cav and it get 28 1/2 miles to the gallon
The Chevy 1500HD truck manages to obtain approximately 13 miles to the gallon in the city, and 18 miles to the gallon on the highway. The truck is popular as it is very roomy, but is quite a heavy user of fuel.