I'm going to be purchasing an '85-'92 TPI camaro here in the hopefully near future. Just gotta find it first!

I did a search but couldn't find exactly what I was looking for.

What kind of HIGHWAY gas mileage can I expect from a more or less stock TPI setup? I'll PROBABLY end up with a 305 TPI car just because they're easier to come by.

Any info is appreciated.

 

25 is about average for a car that's in tune, with a range of between 20 and 30. The higher amounts are possible with enabling Highway Mode in 89+ cars. I've read on here of people getting from 35 to 40mpg, though I'm a bit skeptical myself.

My 305TPI car gets 19 city/24 hwy mpg with typical "youth-enabled driving".

 

the stock tpi got 23 highway...

 

I get like 14 if im lucky. why is mine so bad?? i have a 92 305 tpi? well see after i put my new injectors in and my new O2. but thats real bad.

 

My mileage actually got better as I modified my 89 Iroc. It used to get 23.5 highway w/305 TPI, 5speed, and 3.08s. I installed a ZZ4, AFR 190s, miniram, 52mm TB, stock chip(305) and 19lb inj. I was up to 25.5 mpg. Then I put in 3.73s. I never checked it but it's lower now.

 

I once averaged about 28-30 mpg on the highway when my car had the original 305. The only changes at that time where a 3" cat back, test pipe (read: no cat), and a pair of K&Ns. I drove my 92 from Wyoming to S. FL. It had a 5spd and cruise. Now I don't even want to calculate my mileage!!

 

Have you had it tuned? How's the fuel mixture - It could be too rich.

 

An ancient O2 sensor can be worth an easy 2-3mpg. When old they get slow which does't help the computer any.

Also, incorrectly set timing can be a loss of mpg too. As with dirty/leaky injectors. Obviously old plugs/wires/cap/rotor are no good for ignition efficiency. Maybe the lock-up in your converter isn't working. Incorrect tire pressure. Bad alignment. Bad trans. Dragging brakes (stock rubber lines deteriorate and can leave residual pressure on discs). etc, etc.

Could even be as simple as driving style. For example, some peopel have no concept of driving smoothly on the highway, always accelerating and then braking too much when they come up on cars or whatever. Everytime you hit your brakes, you are wasting energy, and thus fuel.

Don't know what the terrain is like in sacramento, but if it's very hilly, that will affect things too.

It all adds up. More than a few of these are probably present.

 

I got about 29 miles per gallon on the highway. It's a 700r4, 305 tpi with 2.73 gears. I would say that I averaged between 70 and 85 mph (specially in the curvy mountain roads between NC and Tennessee). I was really surprised at the gas mileage, because I normally get around 11 mpg in town with spirited driving. :lala:

 

My city mileage with the 305 TPI 5spd was always low, around 13 mpg and my highway was always high, around 30. I was pleasantly surprised the first time I went on a long road trip. This was also the first car I had owned that had A/C, cruise, and a nice stereo all in one!! I feel 3rd gens are good highway cruising cars! Of course they make even better race cars.

 

I have tuned it up. I have accel cap and rotor, msd super conductor wires, autolite plugs with less than 2k on, edelbrock headers, dynomax catback, K&N throttle body Filter charger and an air foil. I really think its my injectors now I changed the O2 sensor and it didnt do much for it. seems like its runnin bout the same. ive been trying to get my computer hooked up to my ecm in aldl mode so I can see the air fuel ratio but no luck.

 

Don't think you're gonna get 30mpg just because everyone here claims to. I'm getting between 20 and 22mpg highway with a 350 tpi auto with about 350 horsepower. With a badly running 305 I was lucky to get 20.