Just completed 1300 mile round trip in 2005 RL. I had over 60,000 miles on car before the trip, but this was my first long trip experience in the car.
Trip Stats:
averaged 70 mph
top continuous speed 85
most of trip at 75 to 80
mpg = 23.5 overall

Only problem was Navi reset 6 times - 3 on outbound and 3 on return. Wish I would have noted location on outbound to see if it was geography related.

Other than Navi, car was great, very solid. Did not have to deal with any weather other than head wind partially coming back which kepy mph down a bit.

 

I'm a little surprised you didn't get better mileage. I've been on a couple of road trips in mine and always got in the high-20's (27.5-29.0). And my speeds were a lot like yours.

And as for the Nav resets, that's only happened to me once. I hit a bump and it rebooted, so I figured the DVD reader got too sharp a jolt. Were your resets associated with bad roads or anything like that?

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Don't recall the resets occuring with bad bumps. I was on Interstates most of the way.
I was a bit surprised by the mileage as well. Do CA cars still have more emmissions than other states?
My commute is half city, half freeway and I average 20 mpg. Although, when I had instant mpg displayed, I was never getting over 25 mpg with speed over 75.

 

with 60,000 miles, you should really do a seafoam treatment. They sell cans of this stuff at autozone. Add this to your gas and oil about 200 miles before an oil-change. Also put it through a brake booster line to really get the motor clean. This will restore performance and MPG. I did it on my TL at 30K and noticed a difference.

 

What does seafoam do to seals?

 

I don't understand. What do you mean by "put it through a brake booster line" ?

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The geography shouldn't matter. I've been on several long trips in my car, including a 1300-mile round trip to Boston, and a 750-mile trip last week to Kentucky, and my navi never, ever reset. This sounds like a problem you need to take the car to the dealer for.

The mileage is a bit puzzling as well for a car with 60k on it. Driving 80-85 mph on my trip last week, climate control on, my mileage was still 25-26 mpg. Did you do lots of city driving, or get stuck in traffic on your trip? That would do a number on mileage.

 

Trip was mostly freeway and I used speed control most of the time. As I said, I never see 25-26 mpg on the instant mpg going over 80.
Anyone else with CA car get better mileage?

Regarding the Navi, I have never seen it reset before.
Strange thing is that I had been having issues with my XM not working on occassion and it worked flawlessly for the entire trip.

 

Seamfoam is supposed to decarbonize the engine, by adding it to engine oil, fuel tank, but mostly to valves and pistons. You are supposed to pour down the intake somehow, or according to the company, use any vacuum line to suck it into the intake manifold. Brake booster line or PCV line is recommended. Seems it would be a lot easier to do it through the PCV. The result is supposedly cleaner valves and piston crowns. Similarly adding to oil and fuel is supposed to clean out rings, fuel injectors, etc.

I have no idea if it works or if it is harmful or not.

Here is a picture of a Toyota Camry starting up after adding in Seafoam via PCV

 

getakey,

How many passengers on the trip? Was there luggage, golf clubs or heavy cargo? To compare to other RL road trips, these should be compared also. Winter and summer grade fuels also vary mileage in my RL. Tires and tire pressure, etc.

 

There are a few vacum lines that lead directly to the internals of the motor, the brake booster line is one of them. by pouring seafoam in slowly, it will help get into the areas where there are carbon deposits which rob performance and Gas milage, such as on the valves.

To the other poster, Somewhere it mentioned on seafoams site or on the can that it also helps lubricate a seals. Also it really isn't harmful, what I have heard from a person who build motors is that Seafoam is basically really high octane fuel, and by letting it in, the motor runs hotter, burning off all the build up of carbon and gunk.

 

[QUOTE=getakey]Trip was mostly freeway and I used speed control most of the time. As I said, I never see 25-26 mpg on the instant mpg going over 80.
Anyone else with CA car get better mileage?

I get on straight highway driving w/cruise control on at 70-75: 28-30MPG but I have a 2006.

 

I am sure Honda does NOT recommend this or any other additive. Again most Honda engines get wonderful long mileage if they are maintained properly. Call Acura if you think you want to do this.

 

That's what I thought you meant, but I would be extremely reluctant to disconnect those lines and pour something down them.

The brake booster in most cars draws its vacuum from the intake manifold, so anything you pour in those lines would find its way to the intake. In the meantime, though, it might also hang around in the hose(s) and/or get back into the brake booster/master cylinder mechanism itself, and I don't like messing with something critical like brakes.

Just my two cents, but I wouldn't recommend putting anything in those lines.

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tampa - On my trip, had 2 passenger in the car (both light) and minimal luggage. Tire pressure was 34 to 35 psi.

Last night I checked mileage on the way home. Was on long very flat bridge (the San Mateo Bridge for those of you in the Bay Area).
Put Trip Computer with large display of instant mpg on Navi screen and set cruise control at 75. Mileage was exactly 25 mpg for 2 miles. Upped speed to 80 and mileage dropped to 23 to 24 mpg.
Was alone in the car, no noticable wind.

I do not believe my mileage has really changed since purchasing the car as I constantly monitor the average mpg and it is the same now with 60K miles as when new.