U.S. Spec BMW i3 REX: Smaller Gas Tank, No Range Hold, Limited Speed?

As anyone who has driven supposedly identical cars destined for different parts of the world will tell you, there are always a few key differences between how they’re set up for different markets. Traditionally, trim, standard-fit items, entertainment systems, engine specification and even physical dimensions can vary from country to country, with customers in one market often wishing they had the features offered as standard in another.

Are U.S. BMW i3 REx buyers getting a car with a smaller fuel tank, limited top speed and no range holding?

Are U.S. BMW i3 REx buyers getting a car with a smaller fuel tank, limited top speed and no range holding?

It appears the all-electric BMW i3 and its range-extended sibling, the i3 REX (BEVx) is no exception.

Just weeks away from the i3 U.S. Sales debut, BMW has been busy training staff from dealerships across the nation on its first mass-produced plug-in. As a consequence, the differences between the U.S. i3 and its European sibling is starting to show.

What’s more, the changes — specifically those applied to the i3 REx– won’t make everyone happy.

As BMW MiniE then ActiveE Electronaut and i3 reservation holder Tom Moloughney posted yesterday on his blog, information coming out of BMW’s official training sessions seems to point to some differences between the way the i3 REx operates in the U.S. and in Europe.

Smaller fuel tank

Most noticeably is the difference in gas tank size between U.S. and European i3 REx models.

In Europe, the i3 REx’s fuel tank is 9 litres — 1.98 gallons imperial or around 2.37 U.S. gallons. But, says Moloughney, U.S. dealers who have been to the training are quoting a fuel capacity of 1.9 U.S. gallons.  That’s an equivalent drop of 21 percent, or in other words, a range-extension of about 50 miles per tank instead of the 80 miles or so offered by European models.

The reason? We’re not sure, but here are two possible explanations.

The first revolves around fuel bladders, although we’re not sure if the BMW i3 even uses them.

In a certain generation of Toyota Prius hybrid cars, the fuel tank contained a flexible fuel bladder, a flexible membrane which expanded and contracted in line with the fuel in the tank. Designed to control the evaporative emissions of the gasoline, it essentially rendered the fuel tank of certain model year U.S. Toyota Prius hybrids smaller than comparable non-U.S. market cars, which did not have the bladder fitted.

The fuel tank capacity discrepancy could be due to a fuel tank bladder -- a different approach to GM's Chevy Volt fuel tank pressurisation.

The fuel tank capacity discrepancy could be due to a fuel tank bladder — a different approach to GM’s Chevy Volt fuel tank pressurisation.

What’s more, the presence of the bladder helped Toyota certify the car as a low-emissions vehicle, since it helped eliminate air — and thus errant hydrocarbons —  in the fuel tank.

For its Chevrolet Volt extended-range electric car, GM took a different approach, pressurising the fuel tank. Like Toyota, it needed to in order to classify the Volt as a low-emissions car under CARB emissions regulations.

It’s possible — although unlikely — that BMW has decided to opt for Toyota’s now discontinued bladder model, the difference in fuel tank size being about the same as the difference between a tank with or without a bladder.

The second potential reason — which is more of a confusion than anything else — could be related to nothing more than a simple misunderstanding.

You see, there’s a difference between UK (Imperial) and U.S. gallons. In its original specification, the 9-litre BMW i3 REx gas tank equates to 1.98 UK gallons, or 2.4 U.S. gallons. It’s conceivable that someone at BMW mistakenly converted the gas tank size of the U.S. market car by using UK rather than U.S. gallons.

Range extender is just that

As BMW previously explained several times, the U.S. market i3 REx won’t have the ability to operate when the car’s battery pack is fully charged in a range-holding configuration. Having driven an EU-specification car, we can confirm that option does exist on this side of the Atlantic.

Forget about charge hold mode: U.S. customers aren't getting it.

Forget about charge hold mode: U.S. customers aren’t getting it.

In the U.S. however, BMW has confirmed the range-extending engine won’t kick in until the car’s battery pack reaches 6.5 percent state of charge. At that point, the range-extending engine will turn on, operating purely to maintain that level of charge.

It won’t Moloughney says, bring the battery pack above that level of charge. Nor will it run when the i3 is stationary. This is different to the Chevrolet Volt, which will run its gasoline engine to recharge its battery pack back to half-full when ‘mountain mode’ is engaged.

Moreover, the only way of disengaging the range extender will be charging the car’s battery pack up, which Moloughney says is in direct contradiction to what he was told last year by a BMW executive who said it would be possible to override the range-extender and use the final few percent of battery power if you knew you’d make it to your destination without it.

70 mph limited speed

Finally, Moloughney reports dealers telling him, the i3 REx will be limited to a top speed of just 70 mph when the range-extending engine kicks in. While he disagrees with it, saying he’s talked to European i3 owners who have driven faster in range-extended mode, this does tie in with a UK report from last year which claimed a BMW i3 REx slowed to just 44 mph on a steep freeway incline when its battery pack was depleted and its range-extending engine was running.

Since we’ve yet to test the BMW i3 REx in that particular situation we’re going to reserve judgement, but it doesn’t necessarily bode well with BMW’s sporty image if the i3 REx does indeed limit speed when the battery pack is empty. Even if that speed is by most standards, just above or just below the legal limit.

More clarity needed

As we covered earlier this week however, it’s worth noting that dealers aren’t always the best folks to ask for information when it comes to EVs — even if they’ve just been on an official training course.

For now then, we’d advise waiting a little longer for early BMW i3 owners to receive their cars and give their own initial reports on each of these issues before determining just what the U.S. specification i3 has or doesn’t have compared to its original European sibling.

Watch this space.

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