Case Study: 45% above EPA?

[vacationtime247]

How good is your fabrication skills? Duct tape and coroplast. Build a Kammback onto the trunk.
VT247

[olds455]

I found gains at highway speeds using the Ultragauge. I could see how much I could feather off the throttle and still maintain speed or just let it SLOWLY creep down. In the Buick, I thought I was doing a good job feathering to just sustain cuise speed at around 36mpg instant, then watching the UG and the speedo, I could feather down to around 43mpg instant. Once up to 55 to 58 mph, I can average 43mpg in the winter and 46.5 in the summer on a 10 mile stretch of small rolling hills at highway speed. The Buick is not happy cruising at less than 55 mph, the convertor locks around there, so above that by three to four seems to make it happy and allow me to feather to a good number. I'm currently at 61% above EPA average. I commute 55 miles in about 70 minutes with a fair number of stops and lights in the 12 miles closest to home. The auto makes it more challenging, but you can probably get there. An air dam helped me quite a bit. Made getting big number averages easier. Not a whole lot of fuel log for the Century without an airdam or other mods. Before adjusting my driving, I could sneak a 30.5mpg tank in the summer and 28.5 in the winter. Now I can get 34.5 on my morning commute when the ambient temps are 40 deg. (higher on the commute home.)

[SpeedyCorky]

between the fact the car has +200k, and is an automatic - i'd say 25% over EPA is EXCELLENT

[wmjinman]

Originally Posted by SpeedyCorky

between the fact the car has +200k, and is an automatic - i'd say 25% over EPA is EXCELLENT

No doubt. But he wants to try to get 45% over.

While doing coroplast (or cardboard if willing to be a "redneck" like me), rear fender skirts may or may not help some, too. They didn't seem to work on my Jimmy (oh, how I wish they would have), but others are reporting good gains from them.

[Fat Charlie]

I'm busting my butt out there and I'm 46% over- with a manual and a route made for hypermiling. Winter's a killer for good numbers.

[wmjinman]

Good point!! But winter will be over soon, so all this "practice" might pay off once the temps warm up & the car starts rolling freer...

[bestclimb]

I find that as long as I am not crawling up to speed or keeping the pedal on/near the floor. it makes little difference how I accelerate. I find that I end up accelerating faster than much of the traffic.

Re your tire pressures You may see very little difference fuel mileage wise between 40psi and 50psi. At that pressure you may begin to see center wear. You should monitor it checking tread depth at 3 points across the tire, recording then checking again in a few thousand miles.

[cfg83]

Fat Charlie -

Originally Posted by Fat Charlie

I'm busting my butt out there and I'm 46% over- with a manual and a route made for hypermiling. Winter's a killer for good numbers.

Oakland is admittedly milder than other parts of the country, but I still think this is an excellent point. I looked at wobombat's fuel log and I see a good start that needs more data.

CarloSW2

[RedDevil]

Modder Nature will help a hand when the weather gets hotter making the air less dense and shortening the heatup time for the engine.
So even if you cannot get to 45% above EPA now, you might when the weather gets above 25C (and use the A/C with moderation).

[wobombat]

Wow that's a lot of advice! I love it.

Originally Posted by 101Volts

I suggest you accelerate slower and keep the load on the engine low; If you have a ScanGauge II or other on-board gauge this is easier/quicker to learn. Try to keep the load under 20, 15-20 at the highest (Though YMMV depending on the vehicle, I'm basing this on the Caravan I drive.) You may also attach pizza pans to the hubcaps though they might start rusting quickly if not painted. Also, 50 PSI may or may not be the most fuel-efficient tire PSI for your car; It may be best to test the FC for various tire pressures.

I have to say that keeping the load extremely low is one thing I haven't tried. Maybe my engine is so old that compression losses make low acceleration more efficient. I'll have to test that. I'm considering the pizza pans. How do you attach them though? and as for the PSI, I noticed an approximately 5% increase in efficiency at 50 PSI rather than 40 PSI. I may be wearing the tires down unevenly though that way. I have suspension problems so I think they're doing that anyway.

I do not have a scanguage yet, but I plan to get one in the very near future. I noticed that the scanguageE is significantly cheaper than the scanguageII. Any opinions on why the scanguageII is better? Any other gauges I should consider? I got a little obdII reader a while back really cheap that would communicate with an app on a smartphone and read out all the info. If it worked, I think it'd be better than the scanguage because you can customize the environment and save graphs to analyze later, but the thing was a piece of junk and didn't work with my setup. Worked with my brother's setup though.

Originally Posted by wmjinman

If your route has areas where you'll be driving at 50 mph or so, grille blocking would probably help. Every time I've tried it, there's been a significant improvement (like 2 mpg).

At your advice, I made a very rudimentary partial grill block, and put it behind the grille. I know it isn't as effective as in front, but I don't want the car to look ridiculous. I'm considering it though. After one day of driving I saw no difference in warm-up time or coasting ability, so any improvement I'm getting from it is probably minimal. And is there a better way to attach it than duct tape?

Originally Posted by wmjinman

And 50 mph might be too high for your car. I was assuming it would be around 50 mph for my Jimmy - that lower speeds might be "lugging" it. But nope, turns out 40 mph was actually the best speed. (and I checked it a couple times to make sure). Too slow for the freeway (I tried it & got honked at a lot ), so then I found NON-freeway routes where the speed limit was closer to 40.

I've found that my tranny shifts into top gear between 45-50 at low loads and I can maintain top gear as low as 42, but you have a point. I could go slower on the freeway. Just today I found a RV thing going 45-50. That was a real gem. But a civic hx got the drafting spot right behind it. I just followed so people wouldn't blame me for the slow speed. I can get closer to 45 without causing a real disturbance though. And I haven't found any good non-highway routes that don't contain a plethora of stops, which I think would decrease my fuel economy, unless if I coasted to a stop which then would take forever.

Olds455 your MPG numbers are impressive! Especially since our cars are very similar. I don't think I have what it takes to do an air dam, but I'll consider it. And a kammback is way over my head. I'm also considering rear fender skirts. I'm not entirely sure how to attach these sorts of things to the car though.

Originally Posted by cfg83

Oakland is admittedly milder than other parts of the country, but I still think this is an excellent point. I looked at wobombat's fuel log and I see a good start that needs more data.
CarloSW2

My car has some vacuum problems with the fuel system, where the gas pump will cut off at random points for no apparent reason. It makes it really hard to accurately measure MPG, so a lot of fill-ups have gone unrecorded. Winter here probably has only decreased my fuel economy by about 5%. I've been averaging 20-21 through the winter, but I certainly could do better.