I drove my 1987T, 760 wagon, B230FT engine, 250 highway miles this weekend approx. and it used over 3/4 a tank of 89 octane gas.

Is this about normal (i.e, 20mpg)? That's not much better than my gas hog Trooper SUV.

Thanks.

Twenty is what I WAS getting up to a couple of months ago. It turned out that I was developing a gasket leak, so the mileage slowly dropped down to the 15 mpg area. That's when I brought it into the shop, and they discovered and fixed the gasket leak. over tat same weekend, I also replaced the top turbo hose and air filter.

...but something's gone wrong, and I am stumped. It runs great, but my gas mileage has totally tanked (no pun intended). I'm talking around 8 mpg! It looks like everything's hooked up OK, and I'll be bringing the car back into the shop on Tuesday for them to check.

Would that fuel-pressure-regulator thing cause a sudden drop like that?

Bill Meade

'89 740 B230ft, 225kkm (140k mi)

My 1991 940 Turbo Sedan gets about 20 in town, 24-25 mpg on highway. I am not shy about using my right foot. Wife's 1995 945 Turbo gets closer to 22 in town, but she drives more conservatively.

BTW, I used to be perplexed by the fact that my wife's car got like 60 more miles to a tank than mine. Then I discovered that my car has a 16 gallon tank, wife's is 19!!!

Well, I have an 89 760T, 104K and I would KILL!!!!!!!! to get 20 MPG. I'm getting 16 MPG in a mixed commute. I'm using 89 octane. I've pressure tested all my hoses between turbo output and throttle body to 20 PSI with no leaks. I've checked all my sensors, catalytic convertor and mixture. Don't seem to have any smoke out the tail pipe, etc. Checked for vacuum leaks, changed injector seals and a few pounds worth of assorted sensors, filters and seals. I AM ready to kill something....the CAR! Thanks for listening, I feel better now. I'll keep trying 8^(

I was getting about 15, sucked on the fuel pressure regulator, tasted gas, swapped it out with a $5 boneyard unit, now better than 20.

cheers - dave

Thanks for the response Dave. My fuel pressure regulator was one of the few pounds of things replaced. I have yet to check fuel pressure though. I think I need to do this even though I have a new filter, check valve, and FPR.

I'm getting 28 mpg at 60 mph. You might want to check the exhaust during boost. If there is blsck smoke, it's running rich. If this is the case, the most likely cause is a boost leak. Check all your hoses for splits and tightness. Look carefully at the short connecting hoses at the intercooler pipes. The can look ok at idle and bleed pressure during boost. Check the intake manifold gasket for breaks. Check the 700/900 FAQ via the link below.

The turbo seems to make a big difference. My non-turbo 740 wagon gets about 24 around town and 25 - 30 on the road. Of course, it's not going to win any races either!

PM

i get about 20-22mpg in my '87 760t wagon w/200,000 mi

but i push it fairly hard rarely less than 80 mph

My 87 745T APC Auto 218000 gets

19 - 21 mpg city

Highway

55mph 28 mpg

65mph 25.5 - 26 mpg

70mph 23.5 - 24.5 mpg

My '87 745T with the M46 manual tranny gets 27 - 30 mpg on the highway during the summer. The mileage drops to 25 - 27 during the winter. My wife's '88 745T with the AW71 automatic tranny gets 25 - 28 highway during the summer, and 22 - 24 in the winter. City driving is a different story. The '87 does about 25 mpg city during the summer, and about 20 in the winter. The '88 does about 21 mpg city during the summer, and maybe 18 during the winter.

I suspect the mileage difference is mostly due to the tranny differences. Except for the fact the two cars have different turbo charges, (Garrett T3 for the '87 vs. a Mitsu. for the '88), the engines are virtually identical. Maybe the roof rack on the '88 is also hurting me a little. The arguement I hear for not putting a lockup tranny on the automatic turbo cars is to allow the engine to rev a little more to get the turbo spinning when the gas is pushed in. Thing is, a manual tranny is the ultimate lockup tranny, and it works just fine with a turbo. I think the lockup torque converters in the automatic trannies can't take the torque, so the issue is more of durability.

One thing I noticed in your post is you are using 89 octane gas. The owners manual I believe calls for 91 octane. With lower octane, the knock sensor may be kicking in and calling for less ignition advance. This could result in lower efficiency, hence lower gas mileage. I always run 91 octane, pay the difference in gas, and live with it. Cars seem happier. And they run great, and give reasonable mileage for turbo cars.

I'm running 89 octane in mine and I checked mine at 28 mpg at 60 mph, 37 miles one way to work. Since I put the g-valve in it, mileage is down because I'm using the turbo more! But not too much more mind you.

At the low end, but not uncommon at all. Manuals usually get a couple of mpg more than automatics. Most of the figures I read are in the low 20s. Some are right around 20 mpg. Some are in the 25 to 30 mpg range, but this is pretty rare (for a Turbo, which uses more gas and never came with a lock up torque converter). I have never done better than 24-25 mpg, and average 20-22 mpg. I do not drive for economy, so 20 mpg for me may be good.

Philip Bradley

James:

I get from 21 to 22 mpg with my 1986 765T wagon.

You are right on the money. We get better mileage w/ high test.

It is pretty hard to keep my foot out of the turbo esp. in the city. The car is too much fun to drive around like an old lady.

Still, even with "spirited" city driving we get a steady 20. Hwy is never much more than 24.

1990 740T 110,000

UNI

I get 250 miles in town on 13.5 gallons of cheveron 89.

Robert.

1990 740 auto, 54k no turbo