|09-27-2002, 05:58 PM||#1|
Join Date: Apr 2000
Poor Gas Mileage
I bought my wife a 95 SL1 automatic with 85000 miles on it.
It runs perfectly except the gas mileage is very poor compared to my 96 SL2 with 5-speed manual.
The SL2 manual gets 26 mpg/ mixed driving with AC on.
The SL1 automatic gets 19 mpg/mixed driving with AC on.
I know the automatics are less efficient than manuals, but I didn't expect this much difference.
The tire pressures are fine. I wonder what it could be.
Has anybody noticed a significant difference in performance and mileage with the transmission switch set to "performance"
the SL1 gas mileage pales in either setting compared to the SL2.
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|09-27-2002, 06:06 PM||#2|
Join Date: Oct 2001
Do you have any records of when the cars last tune-up was? Simple things such as bad spark plugs or spark plug wires can really affect gas milage. MY SL2 dropped down from 32mpg highway to 26 mpg. I replaced the plugs and wires, and the gas milage went up to almost 34 mpg.
I would do a good tune-up on the car and then see how it the gas milage is.
|09-27-2002, 08:50 PM||#3|
Join Date: Sep 2002
Location: Pennsauken, NJ
Just for reference, my old 140000 miles SL '93 manual (burining 3 quarts/1000 miles ) gets 30mpg city and up to 38 highway ( driving 60mph steady ). Mixed is about 33mpg, I guess.
|09-28-2002, 04:20 AM||#4|
Join Date: Jan 2001
Location: Southern California
Indeed, the auto v. manual were only off by about 1-2 mpg EPA, whereas the SL1 v. SL2 were better by about 5 mpg. So, your wife's car should be doing better for sure. My car has 110k miles, and seems to run fine except my mileage recently dropped from about 28-32 mpg down to about 22 mpg. Granted, my thermostat is stuck open and takes a while to warm up. But I have cardboard in front of the radiator, so when it is warmed up, it stays warm even when on the fwy.
But the drop in mileage occurred after that. With that in mind, the concensus here was to first fix the known problem -- coolant system. While coolant drained, change the PCM coolant temp sensor which helps determine air/fuel ratios. The part is about $15-20. If that doesn't fix it, then change the O2 sensor, which also helps the PCM determine air/fuel ratios, but costs $45-75 depending on where you get it.
Since it's a 95, you can retrieve any engine error codes yourself. That may point you in the right direction if indeed there are codes set:
Otherwise, it sounds like your car may have the same problems as mine. Does it warm up quickly and then stay at around the 1/2 mark when running? If the thermostat seems OK, the coolant temp sensors seem to fail often -- if it's the original, it was prone to cracking, and has been replaced by a new brass housing.
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