Hello, I live in a tropical city (singapore) and it's summer all-year round. It's a South-African made H3, RHD, and i always run it with the AC on. There's also a lot of city-driving.

It's my first week with this baby and i got 330 KM from 73 liters of fuel, which translates to roughly 10MPG –*that's H2 fuel mileage! I sent it to the mechanic, and he checked it, and everything seems okay. I'm out of ideas. Does anyone have any clue?

 

With stop and go traffic it is going to get about 10 mpg and the heat doesn't help either. About the only thing you can do is start upgrading the truck.. intake, exhaust etc... Btw what year model for the H3?

 

An H2 would have gotten 7 mpg in that kind of traffic

 

I see... dammit. 3.7 liter engine, only 17,000kms on it.

It's built in 2009, just before the Hummer brand vaporized.

 

i do nothing but stop and go in rush hour traffic and I'll still average about 16 and its an adventure package. something is causing the loss.

 

first, what is the octane rating of the gasoline used over there? do they use any additives for a more tropical climate there? we use 87 in the states. if fuel is not the issue then check your 4-wheel drive controls to make sure youre not in 4-hi, 4-lo. if that is okay then i would start by taking off all mods done to the engine or wheels. return the truck back to the factory condition and original tire sizes. take off as much additional weight through accessory add-ons, roof-racks, etc. to reduce the curb weight. then drive it around to see what you get. another possibility could be the internal computer that regulates the fuel consumption and may have to be recalibrated. im sure the experts on here can explain in better detail than i..... good luck and keep us posted!

 

Octane rating in Singapore is very high. I use 95. The standard for most vehicles here is actually 98.

Yes, it's in 4-hi all the time (if it was 4-lo the tranny would be gone by now...).

The weather here ranges from 33-40 degrees (91-104F) centigrade in the day, down to 25-28 (78-82F) at night.

There were no mods, I added adventure package items, under armor, side-rails, overhead off-road lights and switched to 33-inch tyres.

Original form, never modified. Mechanic hooked up a diagnostic comp to the vehicle, everything reads fine. I just don't get it.

I'm just wondering if it is because I always run it with the AC on?

 

AC on and lights up top do not help. Your driving style is the LARGEST impact on MPG. If every time you start you stab the gas, and then break hard when stopping, anybody can kill MPG.

H3s are heavy, slow and easy starts are important.

However, 10MPH doesn't sound right. Have it put on a tech scanner and see what the 02 sensors are doing as it come up to temp.

BTW your octane is not measured the same as here in the N. America, your numbers are higher, but the octane content is the similar. The US and Canada measure octane by AKI, Singapore uses RON. H3s require a minimum of 87AKI, which is 92RON, 89AKI is our PLUS grade is 95RON, and our PREMIUM in most of the US is 93AKI which is like your 98RON. So actually, you can run 92RON with no issues and save some $$ as a stock PCM can do nothing with the additional octane you are burning anyway.

 

I guess you do not know singapore stop and go traffic

 

haha...i don't, but when it takes me an hour to an hour and a half to travel 30 miles each way to work thru portland(all freeway) i think i can say i do some stop and go driving. And beleive me, i thought i was gonna be in for 10-12mpg myself the first week i started this commute. I am amazed that i average 15-16 and how consistent my gas mileage stays no matter what the conditions are. mine is an 06 and 3.5l to be fair though.