Ok so a few months ago I had an ignition issue which (thanks to everyone on this forum) was fixed. While I was in the whole ignition theme, I replaced the coils, amp, wires, and distributor cap because even before the no start issue, the car idled bad, and accelerated rough. Before this whole extravaganza, my trip computer told me I was getting about 12.5 mpg. (A mix of city and highway miles).

After the repair I started to get insanely good fuel economy according the the computer. Lucas cheered me up at first :-).. Now I was getting 18 mpg. But then it got unbelievably good like 28 average mpg on one tank, not to mention the fuel burned mode was not at all corresponding with the gauge.. THEN the cars idle started surging rapidly from 700-1200 rpm. So I got them to send me a new amp which fixed the idle but now it says I get 8 ave. mpg! What can I trust?!

 

Manual calculation based on actual fuel used and mile travelled. You can then match it up against whatever your computer says.

 

+1......check using both methods and go from there!

 

+2...manual is the way to go

 

do it yourself....how often do you actually check you "inst." ????

sometimes my works....

alot of the time it will simply read 0 and that still calculated into the computer. Atm my car says i get about 11 mpg.

2 weeks ago i checked (manually) and I got 18.6mpg driving regularly to work and having a little fun on the highway.

honestly whoever says these cars get bad gas mileage can go somewhere...its a 2 ton v12 and it gets almost 20mpg?? stfu

 

What kind of mpgs can be expected of a 95-6 xjs?

 

average about 17 mpg in a mix of city and highway driving.

If you stay on the open road, you can get around 24mpg, maybe even more. I've read posts where people got closer to 30, but they were really thinking about it.

Staying in the city can get you about 15mpg.

 

I get 17mpg mix driving with 91 octane fuel. Don't know how people can get 30.