Actual 80mph Interstate MPG

[thrab]

Originally Posted by jdpm

Thanks for the replies everyone. This is making the Jetta look even more promising for me - especially since I have just seen an ad today for $4k off all remaining Jettas in stock! john

Might want to check that means TDI. I've never seen a TDI sale yet.

[Keithuk]

Hi guys.

First post on here though I've been on other VW forums for 10 months or so.

Now quoting mpg figures the only thing you can show is whats displayed on the MFD (memory 1). Now cruising on a motorway can show different results depending on ambient temperature, wind direction, road surface, tyre pressures etc. Cruising at 70mph for a few miles will show 56mpg, cruising at 80mph for a few miles will show 54mpg.

Now you will find that memory 2 the overhaul average will always show a slightly higher average that actual calculated (full tank, use it, fill tank and calculate). Thge highest calculated average is 43mpg and the lowest was 38mpg for my GTD, I've had the car for 6 months.

Fuelly, Golf GTD (170PS)

[Keithuk]

Originally Posted by thrab

Having the A/C on is not going to hurt your mileage at all.

Oh I forgot to mension about this reply. Anything that takes power of the engine uses fuel I don't care what you say.

I was cruising on the motoway a few months ago and I noticed it was getting warm in the car. As I've said previously it will show about 56mpg at that speed on that day. I put the AC on and mpg slowly dropped down to 51.4mpg. As the car cooled down I switched it off and it slowly went back to 56mpg again.

I left it for another 30-40 miles then put it on again and it dropped by 5mpg each time. Now depending on the system and engine it can knock off 5-7bhp, so are you still saying it doesn't affect the mpg?

I'm not that bother as in the UK its not really need AC, I know AC dries the air as well?

[thrab]

Originally Posted by Keithuk

Oh I forgot to mension about this reply. Anything that takes power of the engine uses fuel I don't care what you say.

Really now. Does that mean you're not even going to consider my response?

I left it for another 30-40 miles then put it on again and it dropped by 5mpg each time. Now depending on the system and engine it can knock off 5-7bhp, so are you still saying it doesn't affect the mpg?

Yes I am going to say it doesn't affect the mpg in any noticeable way. It doesn't really take BHP off so much as it a product of the torque. I've not noticed having the A/C on affect the displayed mpg at all. Also the onboard display is not where you want to go for accurate data anyways; the algorithm to generate the numbers is far from perfect. It is very susceptible to inaccuracy the more uneven terrain is involved.

I'm not that bother as in the UK its not really need AC, I know AC dries the air as well?

Was this a question? Yes it does put out air with lower humidity.

[Keithuk]

Originally Posted by thrab

Also the onboard display is not where you want to go for accurate data anyways;

But the MFD reading is the only one you can go by straight off.

[freeflyer]

I got a 2010 JSW with DSG.
I drive 340km Montreal Ottawa return everyday (340km 211 miles)... average speed 115 kmh which is 71 mph. Over the last 18000km (~11100 miles) including 5% City driving i get 5.8l per 100km (40.55 mpg). And my a/c is always on, tire pressure 40.5 psi.

[mar]

My three long trips Philly to Boston, Reston, Va. and Gettysburg, PA were 50, 51 and 53 mpg going at 58 miles per hour. 65 miles per hour takes it down to like 44mpg. I have gotten 60 mpg on a short 15 mile trip near phiily on route 476 southbound. So whats the rush?

1800 rpm is the optimal mpg speed. Add Good Year fuel max tires and the taylor couple got 68mpg for the world record in Guiness.

[ChrisHo]

Originally Posted by thrab

Having the A/C on is not going to hurt your mileage at all. Having the windows down will definitely hurt it though! Honda makes some good gas engines, very nice fuel economy and just enough power. Still, prefer the TDI to get ridiculous torque for the mileage.

You don't actually believe that do you? I can see the difference in a tank of gas using the AC costing me nearly 2mpg on average.

Consumer Reports has done extensive studies on using AC versus having the windows down, guess which one burned fuel.

[balocco211]

Solid 80 mph cruise speed last weekend; Occassional boost to 87 mph; distance was 213 miles each direction (with an additional 68 miles each way at 70 MPH) averaged 39.6 with 8 mph headwind returning home. (AC used on way there) driving terrain was flat eastern Oregon.

Ave: 39.4
Tire Pressure 36 psi all around
8888 miles logged.

Not as good as the 2005 PD JSW - but enjoyed Sirus Radio.

[thrab]

Originally Posted by ChrisHo

You don't actually believe that do you? I can see the difference in a tank of gas using the AC costing me nearly 2mpg on average.

Consumer Reports has done extensive studies on using AC versus having the windows down, guess which one burned fuel.

Yes I do. The smaller the engine the more pronounced the difference is going to be. The TDI has so much torque it is negligible. You say gas, are you meaning diesel as in you tested your TDI? I've tested during April (month I got my car) when I didn't need A/C and could keep the windows up. I noted no statistical difference. I'll test again this fall now that it is broken in and see if there's a difference.