For a while it seemed like I was getting good mileage but now lately I've just been putting in $20 here and there and it seems like it sucks up the gas no matter how I drive. I'm getting good sparks plugs next week though so hopefully that will give it a little kick in the pants. I have a program to measure mileage, I should see what I get. I would guess around 23 or 24 in town before the spark plugs.

 

Well, it wasn't nearly as good as I expected. 19mpg average (on premium) on a short drive around the neighborhood. That seems bad for a small car with a V6. In typical driving I probably would drive longer stretches which would probably bring it up a couple miles per gallon, but still I wasn't very impressed with 19. I was hoping with the mods and some of the little tune ups I've done it would get more like 25 in the city. I'm hoping the spark plugs will make a big difference. If it still has the original spark plugs, they're definitely due for a change. Engine hasn't been feeling too peppy lately. Haven't had the car long though. Maybe a good quality synthetic oil will help too. The oil was changed before I got it but I'm guessing they used run-of-the-mill stuff.

 

Maybe I should take it out for a longer drive since the calculation is an average, it may actually be something like 21 or 22mpg with the "upgrades" I've done, but about 20mpg is what the car's typical estimated city mileage is and 25 on the freeway. I know it's not an economy car or a hybrid but I would like to get that up to 25 in town and 30+ freeway, maybe with the new plugs (Bosch Fusions) and an oil change I will be getting closer to 25 in town. Gas mileage isn't bad for a light driving car, which is mostly what I use it for, but it would be nice if the tank stretched a little further. I also have the K&N air filter which I've heard conflicting reports that it either increases and decreases mileage... so it may actually be decreasing my mileage somehow with the extra air flow. Anyways, I can feel a little more horsepower with the K&N though, so theoretically shouldn't that be helping gas mileage if I'm not racing around?

 

I was going to ask about your air filter, but you've changed it you say?

Fuel filter been done recently?

You don't say where you are located and how the weather is?
Over here in Glasgow we're deep in the middle of winter, cold, wet and generally miserable.

At this time of year I can fully expect to see a drop of perhaps around 5-6 mpg

With the heating constantly on, heated seats, rear window demister, A/C, Electric heated mirrors, lights on most of the time etc etc.......it really drains the system and uses fuel.

Are you in winter mode?

 

04Xtype04, also keep in mind that as the temps go down, the mileage on the X-Type will dip significantly too. I loose about 2-3 mpg if not more during the winter when compared to summer mileage. This is all due to the timing being retarded to help run the engine a little richer and help warm it up.

As for overall mileage, keep in mind that your car is AWD and there are more drivetrain losses than in say a FWD car. Also, to help with the pep of the car, these cars were geared a little lower than most cars (hence why you will notice that the tach is up around 2500 RPM where a lot of other cars are at about 2,000 RPM). This hurts the mileage too.

The best advice other than driving sensibly is to make sure that you have good fluids in the car all the way around and to make sure that you keep the tires well inflated (I run at 40 psi on the fronts and 35-38 psi on the rears). This will make a difference too.

One other thing that you may want to look at is the e-brake levers on the rear wheels. When I see my mileage start to make a down turn, I will normally find one of these is not releasing completely and it is resulting in one of the rear calipers dragging. You can do a 10 mile run and then pull over and see if you have 1 wheel that is hotter than the rest or pull off the rear wheel and look at the e-brake lever and see if the pointer on the e-brake lever is up against the bolt on the back side of the caliper. If you need me to explain this, I think I have a pic in my gallery that will explain this better.

 

Oh thanks, I never thought of the ebrake getting stuck like that. Hope it's not, but I will try to check it. The mileage is probably due to winter. It's been pretty cold here lately and it's when I've started noticing the car feeling a little more sluggish and hungry on the gas. I guess that is good news though, if I am still getting 19 or 20mpg in colder weather, maybe I will get up to 25 in the warmer months (or rather I should say HOT months here). Thanks for the tips! I will retest it after I get the spark plugs in and see if it makes a noticeable difference on my mpg scanner. In the fine print on their website Bosch claims an average 5% mileage improvement with their +4 spark plug design over OEM. We'll see.

 

04xtype04, I have used the Bosch +4's in another modern day vehicle. No gains. Modern day cars have very good ignition systems and the "multiple spark" plugs don't do anything for you except maybe if you have a condition where the engine is running really rich (as the +4 plug would be able to possibly find a way to spark where the standard plug would not). But, that is a rarity that something like that would exist. Keep the money in your pocket for some other upgrade and stick with a basic double platinum plug.

 

Oh, hmmm. Well I already bought them. They were half off on Amazon with a rebate and I had a gift card too so they will actually be free after the rebate. They are iridium too, which are supposed to give a better spark and should last 100,000 miles (considering you have to take the engine apart to get to these things, that's a good thing). As for the mileage improvement, I see what you're saying. My hopes were probably too high. Even a 5% improvement would only equal about 1 extra mile to the gallon, so the results may not even be that noticeable. Earlier this year I installed some NGK Laser Iridiums on a buddy's car and I can tell you it definitely ran smoother and had more pep, but that would be true with most new spark plugs I guess. I think the NGK Lasers are a little too expensive though, but the Bosch's were priced pretty reasonably and with the rebate they are actually a good deal.


NGK had a video explaining that the multi-tip design can actually get in the way of spark for cars not designed for those kind of plugs, so they use the tradition "J" shaped spark plug tips. However, I'm not sure who to believe because Bosch claims they've researched and tested their +4 tip and say it works good in all cars. Also if you check out E3 spark plugs, they also use a mult-tip design, It's kind of a 3 prong tip, and they claim to also have researched tip design extensively for most power and fuel mileage. Anyways, I am going to give the Bosch a try and see how they do. I am hoping they restore some power back to the motor and maybe squeeze out an extra mile or two over my old plugs.

PS I also got a fuel filter, so I will be changing that out soon too. It's something I've overlooked on the other cars I've owned, but it seems important thing since all that gunk from the gas must just stay in there. I'm not sure if that really improves mileage but I heard it can help with performance at higher speeds by allowing the fuel to flow through easier.

 

If I remember correct the rated fuel economy is like 18-19 city and 26 highway, so what you are getting sounds about right for city driving. Don't know that you will ever average around 24 in stop and go driving. I am getting around 18 or so right now in the middle of winter with almost all city driving. I didn't notice any performance gains nor fuel economy increases when I put in my K&N. New plugs might help slightly, but I wouldn't think a lot unless your plugs are so bad that they would be causing the check engine light to go on. As long as your oil is clean and the correct viscosity I highly doubt an oil change would do anything that you could measurably say increased your MPG. From the type of driving you mention your MPG sounds fine. Depending on your location if it is really cold out and you just do a lot of short runs your mileage can drop like a stone.

 

Yea, it's probably the winter temperature. This past month the temp outside has really dropped a lot and it's when I've started noticing less fuel economy. 19 though isn't bad I guess if that's the sticker estimation. It sounds low compared to a Civic or a Camry or something but I guess they are different kinds of cars. Most of my trips are little errands like a mile or two, so that is probably why the lower mileage. It's not horrible though. I put $20 or $25 in and it usually gets me through the week. I used to have a Land Rover Discovery and that thing got 12 miles to the gallon and it felt like I was ALWAYS at the gas station, and that ran on premium too.

 

The fuel economy is what it is. There is NO magic bullet out there to increase the mileage to any degree out there. Anything you read or hear otherwise is all hype. Just like the plugs. If there were plugs that would increase mileage 5% don't you think manufacturers would all have those in their cars from the factory? With the ever increasing fuel economy standards they spend billions of dollars in R&D trying to get an extra tenth or two of MPG out of their cars and if there was something that cost an additional $10-$20 per car to get that much more MPG logic would tell you they would do that. It's all Marketing hype...or bald faced lies. Do routine maintenance religiously and take care of issues that come up like check engine lights right away and that is the best way assure your MPG is the best it can be.

 

Well, I checked the tire pressure, and whataya know, they were all about 5 pounds low so I aired them up. The car rolls a lot smoother now, I can feel it. The engine seems to even shift at better.

Honestly, I've heard the argument 1000x's before that if car makers could do something that would save gas they would, but back in the 1950's there was supposedly a carburetor that got 200 miles to the gallon and it never made it to production.

 

I have done a lot maintenance on my Jaguar x-type 3.0 including a fresh oil change with Lucas pure synthetic stabilizer, oil filter, double platinum spark plugs, new fuel filter, fuel injector cleaning, all intake gaskets, new MAF sensor, cleaned throttle body, new air filter, and I only use premium gas.

I just went for a 100 mile drive just to see what kind MPG I am getting now.

I am averaging 19-21 MPG in the city and 24-26 MPG on the highway. I think this is pretty much the most you can get out of this car, but I am still on the hunt for anything else that would help improve the MPG.