Hello There,

Curious as to what the gas mileage is on cars like mine. if your willing to post yours that would help me determine if there may be an an issue with my 1997 XJ6L. I get about 13.5 miles (Combined) to the gallon with mostly city driving. i have read 15+ combined is the norm. Any thoughts at all would be great. New EGR maybe clean or replace MAS air flow sensor or O2 Sensors? Any suggestions or experience is awesome.

Thanks,
Martin

 

That is very low mileage, although your mostly city driving will of course drive the average down quite a bit.

There are a few fuel mileage threads, and the average for NA cars is usually a few MPG higher than the average combined 18.5 MPG (mostly highway driving) I get reliably with my SC'd XJR6 which of course gets slightly poorer mileage than a NA car like yours.

I'll let others speculate on why and how best to methodically step through checking what might be going on.

.

 

96 Vandenplas.

I was getting average 14.5 MPG. I used techron fuel additive for the Last two tank fill ups. Trip computer now shows an average of over 16 MPG. Not sure if that is helping. I will continue to monitor. My car has 76k miles and have owned it for two years and just put in around 2000 miles. I am pretty sure this car was serviced only if there was an issue and no preventive maintenance of any comprehensive tune ups have been performed. I have been using the same mechanic who has been servicing this car for last 10 years and he confirms the same. My fuel gauge was erratic and would flicker erratically and with techron, is now stable and shows correct fuel levels. I leant from other posts, techron cleans up the fuel sending unit deposits and has saved me some $$.

I am planning on the following soon.

1. Fuel filter replacement
2. MAF cleaning
3. TB cleaning
4. Crank position sensor cleaning
5. EGR valve cleaning
6. New spark plugs.

I am curious to learn what else other experienced users here have to say.

This is an awesome forum and have learnt a lot . This forum is a great resource as I know nothing about cars and since I joined this forum I am a little confident of addressing issues if any.

 

24mpg(Imp) which is 20 US...small city /highway always in sport mode.
Just yesterday fitted Andy's bracket, so will update soon 😃

 

If the missus drives the car she comes back at the end of the week showing 23-24 miles to the imperial gallon. If I drive the car I'm lucky to show 15-18 mpg. Do you think it because my right foot is heavier than hers?

 

I have new plugs, lucas coils, fuel filter. I have completely rebuilt the front end brakes and suspension with all new OEM parts with NOTHING left out. Balanced on a road force machine and cannot even tell I am going 70mph. I cleaned the throttle body 5k ago. She Drives like a dream but seems a bit sluggish out of the gate. The only thing I can think of is the valve cover oil seperator nipple may be plugged up or these 2 items mention above MAF cleaning or Crank position sensor cleaning. I have never tried the Cheveron cleaner and have always thought they were hogwash no offense. Any help would be great.

 

Snookforever.

I was in the same boat like you on any additives in gas tank. My car was very sluggish to pick up until the engine was warm and I could never get a brisk acceleration. I have a neighbor who builds motorcycle engines for police cruisers and he suggested that I try techron for the heck of it. I did some reading on the Internet and after making sure it would not hurt the engine, I went for it. I did see marked improvement in acceleration after 30 miles of driving. The car feels more responsive now.

Try it and see if it makes any difference.

 

aacpa15215,

Exactly which Cheveron gas additive do you use? Is it the Concentrate Plus Complete Fuel System Cleaner By Cheveron?

Thanks,

Snookfever

 

my fuel economy


3.2 25-28 mpg (Imp) on a run, 18-20 around town
XJR 20-25 on a run, 14-18 around town


I have a heavy right foot...

 

The first bottle was complete fuel system cleaner and second bottle was fuel injector cleaner. Before going for fuel injector cleaning service, this was a cheap fix to see if it will work. Follow instructions on bottle.

 

23-24 Mpg (US) freeway driving x300 4.0, Automatic.

 

I never see less than 22 mpg. Pure highway driving will give 25-27 mpg.

 

In the VDP, I can get up to 27mpg highway and usually average around 19 in town.
The XJR-100 seems to get a little worse mileage than my old 2001 XJR. I'm getting 16-17mpg in town and have seen it as high as 22-23mpg highway. Kitty likes her petrol.

All figures US mpg.

 

I've had mine since 1999. Mileage around town has ranged between 13-18. Highway 20-24. Currently, I am in the 13 - 20 range. I think part of this is due to the change from catalyst down pipes to non-catalyst (JAG OEM pipes by the way) and the rear/2nd set of O2 sensors not giving the correct signal. I think I need to put spacers to get the check engine light off. I still have the rear converters, but I think I may take these off as well as I think they are starting to fall apart inside.

 

15 town, 25 highway and I check regularly. Personal best: 26.5 Hot Springs to Dallas in August last year.

I live in a hilly area and daily trip to work doesn't go over 35mph.

55-70mph trips over 15 miles 2-4 times a week.

Gas: Shell 93 or Valero 93 10% Ethanol or less most of the time.

Oil: Valvoline Maxlife High mileage Synthetic Blend 10-40 or 20-50
Filter: Wix
Plugs: Champion RC9YC (Thank you forum for all the discussions on plugs)

 

New X300 48km 500 miles at 29.8 miles per imperial gallon on Highway. Commuting daily 24.7 mpg. Not too bad for 22 year old car.