16 MPG on 93 SSEi, runs fine, no error codes-is this normal?
My stock '93 SSEi has 140,000 miles. I've had it since 122,000 miles, and it has always yielded anywhere from 15 to 20 MPG on 91 octane, with mostly city driving. The average is closer to 16 MPG. It once got 26 MPG on a long trip, but that was a one-time exception. My wife drives this car and is very gentle on the gas pedal.
Once about 6 weeks ago it only got 12.6 MPG and it still ran fine and had no problem symptoms or error codes, so I replaced the O2 sensor with a new Bosch unit (I'm still looking to buy a couple of Delco O2 sensors). Since replacing the O2 sensor I've tanked-up twice - once it got 16.8 MPG and the second time it got 16.0 MPG.
Is this normal for a '93 supercharged engine with this mileage? It has relatively new plugs and wires, rebuilt GM SRTA transmission, new oil and filter, new catalytic converter, new tires and brakes, new TPS sensor, a low-mileage supercharger, and more...I've read some posts claiming 30 MPG or more, but realistically, what'* normal?
My other Bonneville, a '92 SSE */c, gets at least 18 or 19 MPG in mostly city driving, but it'* engine was rebuilt around 40,000 miles ago.
'99 Bonneville SLE, white, 112,000 miles
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