What's your best Highway fuel economy?

[chrafael]

Got 29.9 mpg at 75-90 mph going from Baton Rouge to New Orleans on I-10 during rush hour in my '98 V70 GLT. I normally get about 22 to 25 mpg idling around town.

[JimBee]

My 96 855, loaded with camping gear and driver only, got just about 30 on trip from Minneapolis to Toronto and back. Fuel grade was 87. Cruise was set at 70 along most open stretches.

[mecheng]

1998 S70 T5 with 223,000km

I got 7.9L/100km or 30mpg on my trip to cottage country. Relatively flat, 23°C, 2 other passengers: 1 baby, 1 wifie, stuff in trunk.
A/C on very low, fuel grade 91 Octane

The 24mpg rating is way too low for these cars. I'm happy with those numbers. This engine (HPT) doesn't feel the weight, unlike the LPT which struggles a bit when you load it down. Going up hills is no problem, plenty of power. It really excels when cruising at 50km/hr or so and then you punch it: goes like mad.

[instarx]

So we see the typical problems with this type of poll... some people think if they can get 40 mpg for five miles, then their car gets 40 mpg highway. Others drive long distances and measure the gas that is pumped in at the end of the trip. They do not get 40 mpg. My V70 gets 70 mpg -- if I get to pick which 15 miles I get to test it on, lol.

Probably a better measure would be "What is the most miles you have gotten out of a tank of gas?" For me that would be 510 miles.

[matthew1]

Instarx, I don't disagree, but the outliers in a poll will tend to be marginalized with enough data. It's built in to the science of statistics. With 84 responses (currently), this effect has already happened, and we can trust the poll. But do notice the question is What's your best Highway fuel economy?, which is asking for the top of a car's highway range.

If I could go back to 2002, I'd phrase the question differently. I'd add many more qualifiers.

Having said this, I'll look for — or create if one doesn't exist — a poll here asking What's your average Highway fuel economy?

[matthew1]

New poll created: What's Your Average Highway Fuel Economy.

It has more specifics than this poll. Neither is perfect, but the new one is better because it has more qualifiers.

I'm loathe to change anything on this poll, because it would invalidate what we have already, so I'm leaving it alone. It's not perfect, but changing anything now would only make it worse.

[matthew1]

... and the new poll has exactly one technical difference (beside the poll's question) from this poll: it has an additional choice... 22-23 mpg. It's an additional selection that slots in below the choices in this poll (lowest here is 24-25 mpg).

[instarx]

I wasn't criticizing your poll, Matt - just pointing out the limitations of self-selecting polls in general. People want their cars to get great mileage - its just human. But I have to admit that there are some surprisingly low numbers being returned in the poll. I'm shocked that 12 people have never gotten better than 25 mpg ever.

Just for fun, here is a histogram of my real-life fuel economy for the last 109 tanks:

As you can see I have two peaks: one at 19.1 for mixed suburban driving and one at 26.9 for [mostly] highway. The highest numbers are pure highway.

In case you are wondering, the two low results at 15.2 - 15.8 were when I had a sticking brake caliper, and the 32.8 mpg was a 500 mile trip with no stops with some aero things on the car for fun.

All this is calculated automatically by a site called http://www.spritmonitor.de, which I recommend.

[matthew1]

Excellent post, Instarx. Thanks for your data.

[hausmeister]

I can't even vote, 21mpg is not on there. That is my best so far, although I was not trying to be especially economical. (T5-R auto)
For my 2.0 na s70 it is 30mpg when I drove very slow.

Measured over a full tank.