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Going to be taking delivery on my 16' performance next week. I will be using hold mode as most of my commute home will be freeway and it doesn't make sense to use the battery, also I want to get rid of any sub par gas the dealer put in just in case.

When I re-fill the tank, I will only put about 1-2 gallons in it as my daily commute can be easily achieved on EV alone. My question is, would there be an MPG benefit to keeping a minimal amount of gas in the tank as each gallon of gas is around 6lbs and the gas tank is nearly 10 gallons? I'll also be doing this to keep the gas from going stale as I only travel beyond 40 miles maybe once a month tops.

On a side note, I'm open to a local trade for the performance wheels I'm getting for the stock ELR rims, but only if they are in perfect condition and the tire wear is similar.
 

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I would keep the gas tank full - less airspace for expansion/contraction condensation to form. Less chance of gasoline evaporation, less sloshing around.

Here in the Mid-Atlantic we're seeing a lot of oddball climate temp swings and high humidity. Low fuel is not desirable. Your call.
 

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Discussion Starter #4
I would keep the gas tank full - less airspace for expansion/contraction condensation to form. Less chance of gasoline evaporation, less sloshing around.

Here in the Mid-Atlantic we're seeing a lot of oddball climate temp swings and high humidity. Low fuel is not desirable. Your call.
Thanks for your input.

Does the ELR share the same pressurized gas tank as the Volt? If so, would it not prevent all those issues such as evaporation and condensation that you mentioned? It would still slosh around, but I hope the noise cancelling will remedy that little annoyance lol.

For some reference, I live in SoCal where it's constantly warm and only gets chilly 3 months out of the year.
 

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2016 ELR (silver), 2009 CTS Premium Sedan (red), 2005 CTS-V (red)
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Yes, the ELR has the same pressurized fuel system (press the button and wait for it to be ready to open) as the Volt, so condensation shouldn't be an issue. I think it has a plastic fuel tank, too, but I never remember to look when I'm out washing the car.

I do exactly what you're describing in my 2016: I keep two gallons in the tank unless I'm going on a long trip. It's a little harder to know exactly how much fuel is in the tank now that the MyCadillac app doesn't tell you the exact number of gallons. I've only put about 1,000 miles on the gas engine in 36,000 total miles, so that shows how little gas I've been able to use! Two gallons is just enough to get me to any of the places I'd need to go in an emergency if my battery had been fully depleted. I try to strategically use some fuel here and there so it's not wasted when I'm forced to use it up due to age. I would guess the reduced weight has saved me a few miles of range over the years, but the primary reason is not wasting a whole tank when the fuel gets old.

As far as the wheels go, everyone "says" the performance wheels had to be larger to accommodate the larger brake calipers. I've always toyed with the idea of swapping brakes on my car for the performance brakes, but I like the "real" ELR wheels better. (The Sport wheels are from the Buick Cascada.) If you do try to swap wheels—and the ELR ones fit over the performance calipers—would you please start a new thread and announce it here so other owners know?

I hope you enjoy your new ELR! Especially being a 2016, it's a really rare car.
 

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Discussion Starter #7
Yes, the ELR has the same pressurized fuel system (press the button and wait for it to be ready to open) as the Volt, so condensation shouldn't be an issue. I think it has a plastic fuel tank, too, but I never remember to look when I'm out washing the car.

I do exactly what you're describing in my 2016: I keep two gallons in the tank unless I'm going on a long trip. It's a little harder to know exactly how much fuel is in the tank now that the MyCadillac app doesn't tell you the exact number of gallons. I've only put about 1,000 miles on the gas engine in 36,000 total miles, so that shows how little gas I've been able to use! Two gallons is just enough to get me to any of the places I'd need to go in an emergency if my battery had been fully depleted. I try to strategically use some fuel here and there so it's not wasted when I'm forced to use it up due to age. I would guess the reduced weight has saved me a few miles of range over the years, but the primary reason is not wasting a whole tank when the fuel gets old.

As far as the wheels go, everyone "says" the performance wheels had to be larger to accommodate the larger brake calipers. I've always toyed with the idea of swapping brakes on my car for the performance brakes, but I like the "real" ELR wheels better. (The Sport wheels are from the Buick Cascada.) If you do try to swap wheels—and the ELR ones fit over the performance calipers—would you please start a new thread and announce it here so other owners know?

I hope you enjoy your new ELR! Especially being a 2016, it's a really rare car.
I figured someone had the same thought process as me, even at a weight savings of 42lbs if you're only keeping 2 gallons at all times, that's almost the equivalent of taking one of the seats out.

So from your description, the OEM ELR rims wouldn't fit over the larger calipers? That's kind of a bummer. I hope I run into an owner that's willing to experiment putting one of his wheels on mine, but considering how rare these are, gonna be a hard time finding one. I'm hoping it was just an appearance thing, and it really doesn't look that bad in person as I've test drove one already.

Thanks for the kind words, I've been test driving them for the past month and just couldn't find the right one, but the one I'm closing on is the closest I'll be able to get minus the Kona interior. I honestly could care less for the performance package as I thought it was plenty sporty as standard and just like you, I prefer the OEM wheels.
 

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Going to be taking delivery on my 16' performance next week. I will be using hold mode as most of my commute home will be freeway and it doesn't make sense to use the battery, also I want to get rid of any sub par gas the dealer put in just in case.

When I re-fill the tank, I will only put about 1-2 gallons in it as my daily commute can be easily achieved on EV alone. My question is, would there be an MPG benefit to keeping a minimal amount of gas in the tank as each gallon of gas is around 6lbs and the gas tank is nearly 10 gallons? I'll also be doing this to keep the gas from going stale as I only travel beyond 40 miles maybe once a month tops.

On a side note, I'm open to a local trade for the performance wheels I'm getting for the stock ELR rims, but only if they are in perfect condition and the tire wear is similar.
I don't think stock wheels will fit over the performance Brembo brakes.
 

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2016 ELR (silver), 2009 CTS Premium Sedan (red), 2005 CTS-V (red)
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I'd be happy to try it if you're ever going to have the car in Northern California. Or, you might watch ebay for a cheap/damaged wheel you could test/resell/return.

What Barfalo said is the assumption I've always seen people post. But I've never heard of anyone truly trying it to know for sure. GM may just have put on the different wheels to make it visually distinct, who knows.
 

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Of course it would depend on the wheel and how much material it would have left after modifying for structural integrity, but it's possible to have the wheel milled which any wheel manufacturer can do easily.

Some years ago, I bought some really cool wheels for my 95 Jag VDP. They were supposed to fit but they didn't. I bought them through Les Schwab and they felt responsible for making it work so they sent them back or sent them somewhere who deals with fixing those types of problems and has the milling capability to shave off some rim material. I got them back and they still didn't fit. Sent them back again. Third time was a charm, and they looked amazing and fit perfect. I would think that the people milling them could ascertain the amount of wheel being shaved off and have a good guess as to what's acceptable and what's not. I never had a problem with the wheels.

Who knows, the Cascadia rim might have been the easy way out for Cadillac. It could be that only a very minor milling could be done and stock wheels would fit. Of course you'd have to get someone to measure the brake caliper assembly and measure what's going to be needed and give that to the place that could do the milling. It's not that hard really. Always a gamble of course but I think I would trust a place that does wheel modifications if they think it would be okay. Stock wheel could be just a little too small not a lot who knows. Since you will already have the performance version with the bigger stuff you will have the ability to measure or have someone measure it for you. I know you can buy new or refurb stock ELR wheels through Detroit Tire and Wheel and can order them powder coated like I did for my second set ready for winter tires.
 

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Discussion Starter #13
I'd be happy to try it if you're ever going to have the car in Northern California. Or, you might watch ebay for a cheap/damaged wheel you could test/resell/return.

What Barfalo said is the assumption I've always seen people post. But I've never heard of anyone truly trying it to know for sure. GM may just have put on the different wheels to make it visually distinct, who knows.
I might just take you up on that offer if I ever travel up there, we go to SF from time to time. Around what area are you located in?

That's what I'm thinking, everyone says that it won't fit, but absolutely no proof or experiments after hours of digging through forums. I also looked at press releases for the "performance package" and no mention of why the wheels were changed. Looking at tire rack, the tire sizes for both ELR & Cascada are the same at 245-40-20. I honestly think it's appearance related as they didn't want ELR customers who bought the car to feel like they got ripped off or something.

There are instances where the brake calipers do interfere with wheel sizes, for example the Model 3 Performance has to have 20's, anything smaller wouldn't fit the calipers without modification. But in this case, the wheels are the same exact dimensions, so I don't see why it wouldn't fit, other than maybe the offset which I don't have any data for either wheels.
 

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Discussion Starter #14
Of course it would depend on the wheel and how much material it would have left after modifying for structural integrity, but it's possible to have the wheel milled which any wheel manufacturer can do easily.

Some years ago, I bought some really cool wheels for my 95 Jag VDP. They were supposed to fit but they didn't. I bought them through Les Schwab and they felt responsible for making it work so they sent them back or sent them somewhere who deals with fixing those types of problems and has the milling capability to shave off some rim material. I got them back and they still didn't fit. Sent them back again. Third time was a charm, and they looked amazing and fit perfect. I would think that the people milling them could ascertain the amount of wheel being shaved off and have a good guess as to what's acceptable and what's not. I never had a problem with the wheels.

Who knows, the Cascadia rim might have been the easy way out for Cadillac. It could be that only a very minor milling could be done and stock wheels would fit. Of course you'd have to get someone to measure the brake caliper assembly and measure what's going to be needed and give that to the place that could do the milling. It's not that hard really. Always a gamble of course but I think I would trust a place that does wheel modifications if they think it would be okay. Stock wheel could be just a little too small not a lot who knows. Since you will already have the performance version with the bigger stuff you will have the ability to measure or have someone measure it for you. I know you can buy new or refurb stock ELR wheels through Detroit Tire and Wheel and can order them powder coated like I did for my second set ready for winter tires.
As soon as I get the car, I'm taking off all the rims and deep cleaning them before plasti dipping them anthracite gray. From there I will measure the interior dimension and post them on here and hopefully someone can maybe do the same to their stock ones.

I've seen the stock ELR rims w/ the dark gray finish and if they end up fitting, I'll be purchasing those shortly after confirming they fit. Don't want the whole murdered out look, so dark gray will be a good compromise.
 
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