[exclusivedetails]

Alright so I got my car 2 months ago but finally got my tags on Friday.

Now here comes the stupid questions...

1. If I drive 40 miles in comfort mode, wouldn't I practically be driving with just the 3 cylinder motor once the battery runs out? What MPG are you getting in comfort mode on longer drives?

2. In sport mode, I get 26 MPG. Doesn't sound that great. Is this correct?

[geraldm2012650vert]

I drove to Indianapolis and back. A little over 2,000 miles. I averaged 34 mpg at 75 mph. I got on it when I could.

[StannisTheMannie]

I've done as well as 55mpg on long highway runs, and as little as 15mpg (tail of the dragon). But my average for around town with mix of electric, comfort, and sport seems to be in the 26-30mpg range. I tend to also have a heavy foot, and use sport mode a bit more than BMW probably anticipated. I've never really used the eco-pro mode either.

[zagaboo]

I use mine as daily driver to commute between my offices. Typically drive at up to 70-85mph on motorway for 50 miles, then 10 miles stop start into city (and return journey) and get high 30's/low 40's (uk mpg). Over life of car and 8K I've averaged 42mpg (uk). Better than the 19mpg I got in a V8 R8 doing the same kind of driving.

[Aye-eight]

Originally Posted by exclusivedetails

Alright so I got my car 2 months ago but finally got my tags on Friday.

Now here comes the stupid questions...

1. If I drive 40 miles in comfort mode, wouldn't I practically be driving with just the 3 cylinder motor once the battery runs out? What MPG are you getting in comfort mode on longer drives?

2. In sport mode, I get 26 MPG. Doesn't sound that great. Is this correct?

If your battery is not full, sport mode will recharge it. This means the front e-motor acts as a generator, which adds significant resistance / drag to the drivetrain. The energy has to come from somewhere. And it comes from the combustion engine working harder against additional resistance. You're converting gasoline into electricity via the petrol engine. That can never be very efficient, by definition. So it's going to hurt your mpg.

Although I haven't seen any data to that effect, I'm quite sure Sport mode also runs a different engine mapping to make the car more snappy. That will also require more fuel.

The cool thing about the i8 is, you can make it into whatever car you want it to be on any given day. You can drive it as a very quick grand tourer all day long, and get the same efficiency as other sporty cars. Or you can become almost completely abstinent from gas stations if you adjust your driving style accordingly. In the end, it's all in your head and your foot.

It so happens that I drive mostly short trips, and I have plenty of opportunities to recharge. Since traffic and local laws usually don't leave much room for racy driving, I go fully electric a lot. My last fill-up was 1200 km (750 miles) ago, and my tank is still half full. I guess that gives me an mpg of 134 (US).

Do I drive like that all the time? No. And it will never happen on extended highway driving, given the small size of the battery. But often enough, there's simply no point in doing it any other way.

[Nivarox]

I drove a trip of around 362 kilometers in various settings from Comfort to Sport .I opted roughly %80 in comfort mode during the trip .
Average consumption registered 7.7 liters per 100 kilometers .
I must say BMW i8 is the most economical gasoline powered car I have ever driven .I had seen a ridiculous 22.1 /100 liters on the dash in a test car and my initial thoughts was like that "Is this a Range Rover , what gives that ? "
However, on the contrary above I have seen as little as 1.1 /100 kilometers while going 60 kph on the dash computer .I would like to use more Comfort Mode but it eats up E-Drive's battery range therefore I mostly prefer Sport Mode to charge the batteries as well . Not to mention the engine sounds better in Sport Mode

[zagaboo]

Aye-eight hits the nail on the head. if you think about your journey you can adopt drive modes to suit.

For me, it is comfort mode on motorways, which drains the battery range down to about 10 miles by the time i hit the city if i left it in comfort all the way.

However, I want full electric range to get me in/out of the city on battery power, so with 6 miles to go before i get off the motorway, i switch to sport mode and that replenishes the battery at the rate of 1 mile range for 1 mile driven (so long as you continue to drive normal and not hoof it).

You will quickly learn how to pick your moments to top up the battery.

I used this to good effect on the recent 'going green' ipure drive. Had the missus on board and so could really let rip and so used electric mode on the narrow, steep mountain roads, then recharged in sport mode on downhill and wider straights. 2 days driving mountain passes - 44 mpg!

Very clever car!

[mikenyc]

Originally Posted by Aye-eight

If your battery is not full, sport mode will recharge it. This means the front e-motor acts as a generator, which adds significant resistance / drag to the drivetrain. The energy has to come from somewhere. And it comes from the combustion engine working harder against additional resistance. You're converting gasoline into electricity via the petrol engine. That can never be very efficient, by definition. So it's going to hurt your mpg.

Although I haven't seen any data to that effect, I'm quite sure Sport mode also runs a different engine mapping to make the car more snappy. That will also require more fuel.

The cool thing about the i8 is, you can make it into whatever car you want it to be on any given day. You can drive it as a very quick grand tourer all day long, and get the same efficiency as other sporty cars. Or you can become almost completely abstinent from gas stations if you adjust your driving style accordingly. In the end, it's all in your head and your foot.

It so happens that I drive mostly short trips, and I have plenty of opportunities to recharge. Since traffic and local laws usually don't leave much room for racy driving, I go fully electric a lot. My last fill-up was 1200 km (750 miles) ago, and my tank is still half full. I guess that gives me an mpg of 134 (US).

Do I drive like that all the time? No. And it will never happen on extended highway driving, given the small size of the battery. But often enough, there's simply no point in doing it any other way.

statement in red is wrong - i8 has 3 engines and in sport mode using:
front electric to give you 100% to front wheels
1.5L supplies 100% to rear and plus runs 3rd engine/generator to keep battery constantly charged at around 80% to keep front wheels always available at 100%.

Using sport mode to charge your battery and than use this charge to drive all electric will not save any $$ compared to running in eco-pro mode

looks like eco-pro the most efficient mode of all even compared to eDrive mode ( dont forget that electric charge is never free even if its from your friends home outlet - someone paying for it anyway

eDrive only make sense if your average daily commute around 10 miles and charger aways available in both destination and home locations

I did 3000+ miles and my all time average 32.5mpg. I dont have charger in my building but what ever i can I will use my charger which is on average only 1-2 full charges every 2 weeks( one of my offices and vacation place). I like to drive around 80-90+mph on empty hwy and sometimes like to run my engine at 7000rpm for about 3-5 min every day

last night I actually tried Lunch Control few times - and tell you the truth was not impressed at all it feels like my 5.0x6 will kill my i8 in 0-60.... may be since electric pulls from zero rpm and you loose this gas only punch , not sure?

[Aye-eight]

Sorry, my statement is not wrong. It's simple physics. Whichever generator actually provides the recharge doesn't matter. The physical fact is that if you draw a current from a generator, alternator, or dynamo, its resitance to spin will increase due to the magnetic fields (that's why, for instance, it's called "regenerative braking" or why having your headlights on will slightly increase your fuel consumption on any car - there is no free energy). Otherwise, you'd have a perpetuum mobile. So, wherever the recharge comes from, it will increase rolling resistance, therefore make the engine work harder, therefore increase fuel consumption.

When you use sport mode, what happens is this: when you're under full load, the full power of the gas engine will go to the rear wheels and the full power of the battery will go to the front wheels - correct. However, the moment you're not under full load (i.e., not pedal to the metal, or cruising, or coasting) the gas engine will work harder than it would normally have to in order to recharge the battery. Hence, I agree - if that wasn't clear enough - using sport mode to charge the battery is convenient but highly inefficient.

Secondly, Eco Pro and eDrive are not mutually exclusive. You can be in eDrive and still select Eco Pro, which will increase recharge on coasting and braking, reduce auxilliary consumption, like a/c, etc.

Thirdly, eDrive makes sense in more than just short commuting situations, like getting into city traffic after a long highway drive. I have 20'000 km / 12'500 miles on mine, with 3.7 l/100km on average, which is 63.6 mpg (US).

Lastly, I don't know if the i8 accelerates faster than a 5.0 x6. But frankly, it doesn't matter to me. An i8 would still dust any SUV, as sporty as it might want to be, in any spirited driving that involves turns and / or altitude changes. And - I'm sure that x6 burns a lot more fuel, because you're driving around weight and wind resistance.

[zagaboo]

lol. Nice convo with yourself there aye eight ;-)

X6 does burn more fuel fact! I had a 4.0d X6 as a loan car and on my normal work run it did 32mpg vs 42mpg for the i8.

I'd always recommend using sport to top up the electric range before hitting a city - the ride is soooo much better. I8 in the city rush hour on zero battery isn't exactly a smooth experience.

Best tip though, is don't fret about mpgs chaps - just drive it.

[Aye-eight]

Originally Posted by zagaboo

Best tip though, is don't fret about mpgs chaps - just drive it.

Fair point.