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Just read the posts about DRLs and MPG and have a similar question. I have DRLs on my new 2005 RAV4 and I get LOUSY gas mileage. It's a 5 speed, I don't have a lead foot and I'm getting around 20-21 mpg city/highway combined. My husband is wondering about the theory of the DRLs causing one to lose a couple mpg, so we're thinking of turning them off. Short of taking it to the dealer, does anyone specifically know how to turn them off? i.e., if it's a relay where is it and is it easy to modify?

And speaking of lousy gas mileage, I'm sure my rack has something to do with it. I have Yakima low-rider towers, cross bars, and a tandem rack on top of my car. I use it a lot so I don't want to take the rack off and on all the time. But boy, I HATE getting only 20-21 mpg after previously having a car that got around 30 (with the same rack setup). Sometimes I wonder if there is anything wrong with it when I read people getting up towards 27!

Kathy
 
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yes the weight and electricity does effect milage to some extend. ... the bar defintelly does but electricity i wouldn't say so..
i get about 25 per Gallen i dunno if it's the sub or I just like to down shift(floor the gas)..
 

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In my 1997 RAV4, there is a Daytime Running Light relay. There is also a 7.5A DRL fuse near left front strut tower. The location of the fuse in your 2005 RAV4 could be different. To remove it is obviously the most easy way to disable DRL.

DRL may not impact fuel economy significantly because its current is much lower than that when you turn headlight on.
 

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Your rack and the fact that you say your RAV is new have a lot more to do with it than DRLs do. Roof racks create drag up there on the roof, and new vehicles generally use more gas than ones that have been thoroughly broken in with a few thousand miles on them. DRLs just don't have much of an effect at all on fuel economy. My older, less aerodynamic, automatic RAV4 with DRLs but no rack got 27 mpg on my last highway trip.
 
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So maybe I just need to be patient with this mileage thing. I think I might remove the rack (but keep the factory rack on) and go for a bit just to see what my mileage turns into. I didn't realize that as the car breaks in the mileage could get better. Maybe I'll call the dealership today to see if I can find out the exact location of the DRL relay.

Kathy
 
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I've only had my Rav a few weeks, but I'm up to 28.7 mpg. I credit it to shifting up as quickly as possible. I drive up and down three hills to get to work and have only figured out the best gear for one of them, so I'm hoping to get even better mileage after a few more weeks. The car had almost 40k on it when I bought it so it is well past the breaking in stage.
 

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The DRL's have no effect on gas mileage. If that were true, when I am driving on the highway at night with all the lights on, the gas mileage would drop. I do a lot of driving, especially at night, and I keep track of my mileage with every tank of gas I go through, which is usually 2-3 tanks per week depending on my traveling.

Yes, in theory, the higher electrical load on the alternator could put more resistance on the engine and as a result lower your gas mileage, but we're talking an amount that is not statistically significant.

The load that your A/C compressor puts on your engine is far more than the load of the alternator, hence the need for the engine to "idle up" when the A/C compressor is engaged. The A/C does cause a slight drop in gas mileage; for my Rav it's maybe 2 mpg at the most. So if you figure that the A/C drops the gas mileage by maybe 2 mpg, the alternator would have to be far less because of the lighter load compared to the A/C compressor.

Roof racks have a greater effect on gas mileage because they increase the wind resistance (lower the aerodynamics) of the vehicle. Also, your Rav is new so it is not broken it yet.
 

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DRLs have a negligible effect on mileage. On an individual car anyway. If the US did something silly like mandating them it sure would result in a bump in gas usage as a whole.

My wife's automatic FWD '05 RAV gets damn near 30mpg on her commute. It's mostly highway though she is a bit of a speed demon. Never returned numbers like yours. I put some Mobil1 synthetic oil which can slightly boost your mileage in it.

What's your commute like? Strange that an automatic is getting such better mileage.
 

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NRMA is a top auto insurance, road service and traffic policy study company in the state of New South Welsh, Australia. It made survey about DRL all over the world in last a few years. Its report indicates that DRL will increase fuel consumption about 0.5%.

GM estimates the annual cost of fuel for DRLs at less than US$10 per vehicle per year.
 

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GM is DRL's biggest pimp because they want to standardize their production lines but they want everyone else to be forced to do it through legislation too so there's an increase in costs across manufacturers.

Multiply that GM $10 estimate(surely done when gas costs half as much as it does now) by 200+ million vehicles in the US alone...

In any case there has been no valid proof of DRLs improving safety. Heck some studies have shown the opposite.
 
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My commute is only something like 7 minutes of stop and go through lights with a max speed of 45 mph. But I also do a lot of highway driving around the Seattle area off and on. The car only has maybe 3000 miles on it right now. I sure do hope it starts getting better soon as I'm pretty disappointed right now. I'm hoping I can maybe get 25 even with the rack, but that might be a little optimistic.

Kathy
 

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Kathy said:
My commute is only something like 7 minutes of stop and go through lights with a max speed of 45 mph. But I also do a lot of highway driving around the Seattle area off and on. The car only has maybe 3000 miles on it right now. I sure do hope it starts getting better soon as I'm pretty disappointed right now. I'm hoping I can maybe get 25 even with the rack, but that might be a little optimistic.

Kathy
There's your 'problem'. An extremely short stop and go commute. Frequent short trips take a lot more out of a car than longer highway trips.
 

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I've always loved the "GM is behind the DRL conspiracy in order to standardize its production lines" urban legend ever since I first heard it back around 1997. Could have been a great X-Files storyline. Frighteningly, it now seems that Toyota, VW, Subaru and Volvo are also part of the same devious plan to decrease mileage in American cars and cost each owner an extra $10.
 
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