Well, the subject says it all.
I have been getting an avg. of 19mpg in the Z.... mixed highway and city driving. (about 50/50).. No hot rodding, as hard as it is not to...
What should I check out?

Something must be done!
Thanks for the help...

 

I remember your post from a few days ago..............did you ever figure out what gears you have in the back? Check the codes on the driver's door for GU2 or GU5. If you see GU2, that means you've got the 2.73 gears, and let me tell you, they are NOT good for city driving mileage. If you have 3.23 gears, you'll see GU5, and then I'd say you should get pretty good all-round mileage, city and hwy, but TRUST ME, you won't get nearly the mileage you'd like when you throw city driving into the mix........especially if it's ~50% like you said. IMO, there is nothing wrong with your car. Try a 100% highway trip, and you'll probably see mileage in the high 20's MPG (26-28 mpg). Otherwise, 19 mpg for 50/50 city/hwy is about the same as I get with A4 and 2.73 gears.

 

That seems about right... but I have a LT1. I average about 18 mpg 50/50 driving and getting on throttle hard (1st-2nd gear WOT) once per day. Strait highway driving I get ~27mpg. I have a 6 speed though...

I would expect similar city numbers and slightly higher highway numbers for a LS1 car.

 

mine also does 19 on average, i drove it cross country (NY- CA) and the best i got was 25 miles/gal route 15 Kansas , flat no turns no hills, put it on cruise and fell a sleep .

 

Check your tire pressure.

 

"kiztope No hot rodding, as hard as it is not to...
What should I check out?" NOTHING be happy with 19 mpg its normal. I get 12 mpg in town cause I rarely get on the hiways. You shouldnt even consider milage with a 5.7 liter engine. There is nothing effcient about one nor should there be. If it is a concern trade your car in for a 4 cylinder. Your never going to be happy. You have to accept crappy milage hi priced hi octane gas as the tradeoff for lots of power and torque

 

sometimes gas milage can be used as a red flag to tell you there is a problem. It doesn't hurt to keep track of gas milage. Although 19MPG is normal

 

Hey smart guy... did you look at my sig?? What would make you think that I am the least bit interested in a 4 banger....

I am just concerned that my 92 Formula with 184k+ mi. on it gets better gas mileage than my Z.

But since all you guys are saying that 19 is fairly normal, I won't worry about it. I do need to check my gears....

I am gonna check out some sensors and tires... get an air filter and maybe change the plugs if I get a chance...

BTW, Whats the stock gap on the plugs for an LS1?

 

19-20 mpg is pretty normal for an A4 LS1 car in mixed driving.
Stock plug gap is .060 but .050 works better.

 

It could be related to a gearing issue, if the Formula maybe has slightly lower gears than your Z28 so it gets better city mileage, but I've also heard a lot of guys who have (or had) 3rd-gens say that the old L98's "seemed to" have more low-end torque than the LS1's have, so maybe for regular, everyday driving, the '92 would get better mileage on the street? Who knows, but it's just a thought. Also, think about this............the LS1 makes way more horsepower than the L98 (350 flywheel HP vs what, 215 HP or something like that? ) and horsepower doesn't just come from thin air, right? It takes BURNING FUEL to create the power, so maybe it's just the price you pay to have a 13 second factory built car vs a 14 - 15 second factory built car.