BMW i3 Rex Vs Chevrolet Volt – Drag Race Video

OCT 11 2016 BY JAY COLE 42

A few days ago, InsideEVs contributor David Murray (also know as the “The 8-Bit Guy” on Youtube), filed a test drive review on a steal of a BMW i3 REx (range extended vehicle) he picked up last week.

BMW i3 REx and Chevrolet Volt square off

BMW i3 REx and Chevrolet Volt square off

And in so doing promised to take the BMW, and his 2nd generation 2017 Chevrolet Volt, to the drag strip for an impromptu race.

As we know the BMW i3 REx has both a stronger motor and less weight, but much has been made of the latest Chevy plug-in’s ability to pull off the line (one might recall that the new Volt is actually quicker to 30 mph (~2.2 secs) than the original Tesla Model S 85) – which should make for some interesting results at the track.

Check out the video to see how it all goes down!

 

Categories: BMW, Chevrolet, Racing

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42 Comments on "BMW i3 Rex Vs Chevrolet Volt – Drag Race Video"

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Well that’s interesting… So even though Car and Driver says the Volt has a 0-60 that is 0.5 seconds slower than the i3, it beat the i3 Rex on the 1/8 mile and, by extension, the 0-60.

Granted, the i3 raced had the Rex version, which is heavier as noted in the video.

“it beat the i3 Rex on the 1/8 mile and, by extension, the 0-60.”

Not necessarily. The race Volt won – there were two races – because of much stronger initial acceleration, but the i3 began to catch up quite a bit after the first couple of seconds.

An 1/8 mile race is all about covering ground quickly, not getting up to speed.

Absolutely, even a quarter mile race is largely about the launch. Perfect example. Car and Driver tested 6 EVS head to head.The Focus has a much better power to weight ratio, but beats the LEAF 0-60 mph by only .10 seconds. Because of its slow launch (like the i3) the Focus is .60 seconds behind the LEAF to 30mph. So even though slower once above 30mph, the LEAF’s superior launch ends up giving it the win through even the quarter mile by a not insignificant .20 seconds, even though the Focus EV is moving faster. In a 1/8 mile race, the LEAF would be even further ahead. So what this tells you is the from a standstill the even by 80 mph the more powerful Focus still hasn’t caught the LEAF. For the i3 to catch the quick launching Volt in an 1/8 milet race shows the huge difference in power to weight ratio.

http://www.caranddriver.com/comparisons/final-scoring-performance-data-and-complete-specs-page-8

I agree you can’t simply look at power to weight ratio on single speed cars like EV. But if it’s multi-gear, power to weight ratio would apply when going through more than one gear ratio.

For single speed EV, more apt comparison would be average power over X MPH (or X miles) to weight ratio: integrate power over X, divide by X, then take ratio to weight. That requires knowing the power profile, not just one peak power number.

At 1/8 mile both had already gone well over 9 seconds, and the BMW i3 had not caught up at that point yet. So I had been inferring the Volt beat it on the 0-60.

But you’re correct that I can’t infer the acceleration from that overall time/distance. I’d like to know for sure how the BMW with Rex stacks up. 😉

If you look at first run’s 330 ft numbers you’ll see Volt was 53.89 mph at 6.456 seconds and i3 was 57.24 mph at 6.651 seconds. Both cars would be accelerating at ~0.3g at that point, or gaining ~0.7 mph each tenth of a second.

So Volt took ~0.87 seconds after the 330 mark to gain an additional 6.11 mph, hitting 60 mph at 7.32 seconds. By the same method i3 hit 60 mph in 7.05 seconds.

That assumption of constant g force may not apply. SparkEV pulls almost 0.45g under 30 MPH, but much less later in almost linear slope. I suspect Volt will taper much more quickly than i3. Then i3 might be close to 7 or 7.1, but Volt would be much more, maybe 7.5 or more.

You are right. The Volt loses acceleration quickly after 30mph. The i3 accelerates very hard AT 30mph.

I’m not sure if it does accelerates hard AT 30 MPH or if that’s just perception and taper is just less. It would be best if there’s rear wheel power / torque profiles (graph or data) for i3 and Volt so one could analyze like I did with SparkEV in this blog post.

http://sparkev.blogspot.com/2016/06/sparkev-performance-analysis.html

One complication would be static vs dynamic measurement (ie, bhp vs running hp). Some mention sluggish take off on i3, and that may be hidden in static power measurements.

I have done hundred of drag strip runs, and it is easy to interpret these numbers. The i3 has to pull much harder after the initial start to catch the Volt in such a short distance. But unless you totally botch the start, the terminal speed is the telling number when it comes to power to weight ratio. Through all three runs, the 1/8 mile trap speed of each of these cars was consistent and within .15 mph! The i3 always trapping about 2mph faster than the Volt. So put another 20hp in the Volt, and it should equal the trap speed of the i3. But the i3 motor peak really maxes out around 50mph or so, its best acceleration is below 60mph. At the 330ft (halfway mark) you can see the i3 is moving almost 4mph faster than the Volt. 53.52 MPH Volt 330ft 6.835 sec. 57.39 MPH i3 330ft. 6.735 sec This shows the higher average acceleration power the i3 put though the first 330ft. For the i3 to almost hit 57.39 mph in 6.735 sec, chances are it would hit 60mph (+2.61mph) in somewhere around 7 seconds. And for the slower accelerating Volt at 53.52 mph, it… Read more »

Edit: the exact 330ft times I posted above were from the last run, but the 4mph advantage holds true on all the runs.

Also food for thought, the average ET of the i3 through the 3 runs was quicker than the Volt. The quickest run from the Volt and i3 varied by only .039 seconds! The Volt driver always had the quicker reaction time which made it even harder for the i3 to reel in the Volt.

Don’t give the Volt driver’s reaction time all the credit. In my i3 test drive I experienced a significant launch delay in all driving modes. Push the go pedal, breathe in, and then it goes. My i-MiEV would probably post a faster reaction time than an i3. It really seemed that BMW didn’t want to embarrass their gassers with economical electric acceleration.

“So even though Car and Driver says the Volt has a 0-60 that is 0.5 seconds slower than the i3, it beat the i3 Rex on the 1/8 mile and, by extension, the 0-60.” I found this is a popular and often made mistake by average people. 0-60mph is a time to a speed. Race in distance as in drag race or daily driving is a race to a distance. The two are completely different concept but they are related. You can easily have a car that lost 0-60mph in time but win by be ahead of the other car. Let us look at the it graphically. Typically, we can plot the car acceleration on a chart where the y axis is the speed and x axis is the time. So, you have a car A and car B having a plot of curves on the chart. Car A can have a different shape curve than car B. That area under the curve is distance covered. So, technically you can have car A reaching the 60mph faster than car B but have less area under the curve. That means car A lost the race by being behind despite that it… Read more »

Yeah, I definitely realized my error after I stated it. I understand that I can’t measure acceleration performance as a function of simply speed per unit distance.

Noted my error in my own response above, but kind of buried at this point. 😉

Haha, I even stated it wrong here again, but yes, I realize the two concepts are similar but different. 🙂

The i3 is so sure footed in the rain, I can floor it and launch with no wheel spin or dsc intervention. Compared to my much slower Focus EV which still wants to spin its tires uselessly in the rain at 30mph. My LEAF was much better, but still didn’t compare to my i3. Never even heard a tire squeal in dozens of 0-60 mph tests. The i3 is deadly consistent. My BEV runs consistent 6.4-6.5 second 0-60 times. In comparison, while fighting traction for inconsistent runs, the best we managed in a brand new Spark EV was 6.9-7.0 sec. Inherently I think the rear wheel drive,rear motor configuration gives the i3 a huge advantage in off the line acceleration and cornering responsiveness through canyon roads. The other weekend I raced up to the top of Mount Wilson running down some lowered Civic and two motorcycles.Once I hung on tightly to the grab handle to brace myself and pushed my i3 through the mountain roads, I learned this thing handles amazingly through those tight 30-45mph turns. I took some 25 mph turns at close to 50. So although it feels uninspiring with its tall stance and unsupportive seats, you really… Read more »

I’ve owned an i3 for over a year and also never heard a tire chirp a single time, no matter how aggressive I’m driving.

I drove a second gen Volt for literally minutes before accidentally chirping the tires.

RWD FTW.

“I think the rear wheel drive,rear motor configuration gives the i3 a huge advantage in off the line acceleration and cornering responsiveness through canyon roads”

So true! One would think GM learned from SparkEV’s tendency to want to spin the tires, but noooo. Bolt is still FWD. Ugh!

“The same trip in my LEAF was made with high anxiety”

Why would leaf be so much worse? Range wise, it’s rated longer than i3. Is it due to worn out battery on Leaf or is it because Leaf is heavier?

2200 ft elevation gain over 30 miles with SparkEV uses almost exactly 40% battery and 4.2 mi/kWh. 5000+ ft will use close to 100%. Seeing how i3 is EPA 81 miles vs SparkEV 82 miles, 30% remaining at top of 5000+ ft with i3 seems incredibly good.

“Spark EV was 6.9-7.0 sec”

By the way, you mentioned uploading this video, did you get a chance to do it? I’m surprised SparkEV is quicker than Chevy’s web site figure and i3REx tested here. Did SparkEV use after-market stickier tires?

If that’s true of SparkEV, that could rival Bolt as Ampera-e is 7.3 sec to 62 MPH.

If the Ampera only does a 7.3 second 0-60 time then the Spark would definitely beat it. But I though Chevy advertised the Bolt will have sub 7 second 0-60 times?

Here is a 7.0 flat 0-60 time in a new Spark EV

Whereas the Volt would need at least 30 more HP to make up the 4mph trap speed difference at the 330 mark…the BEV being almost 300lb lighter than the REX has about another 25hp advantage in acceleration numbers over the Volt. Maybe I can find a new Volt to do a side by side with my i3 BEV 🙂 Still wondering, was the Volt engine running at anytime during that drag strip run???

No.. Both cars were in pure EV mode.

Personally if a car can do a 0 to 100km/h under 15s, I’m OK with the car.
Under a 10s his not even my top 10 goals to buy a car.
But if you ask me to choose between the Vol 2 and the i3 33kWh REX, I will choose Volt 2. Even I prefer a ~4m cars, the Volt 2 is really a good car, and Chevrolet have done very good job.

I don’t know, Seuthes. Merging into traffic is a lot easier and way safer if you can get up to speed in a hurry. I think 0-60 is a very good measure of how safely you can merge with traffic. And if you take more than 10 seconds to get to 60, you are getting in the way of others way too often.
Under 10 is base level, under 8 is nice, under 6 is great!
The thing to remember is, electric cars by their very nature are torque’y/quick. BEV makers should be taking advantage of that fact. Flip side of the coin, if you drive fast for long in a BEV your AER drops like a rock. So emphasizing quickness is ok, but fast, not so much.

Yeah… I don’t know about the 15 second thing.. I test drove a C-Max Energi and put it in EV-Now mode. In this mode, it really does take around 15 seconds to reach 60 mph. I felt that the car was plenty capable of driving around in city traffic that way. But trying to accelerate above 45 mph was really a struggle. I would not feel safe merging onto a busy highway in EV now mode in that car. A Prius is around 11 or 12 seconds (depending on model), which I have driven many times, and I would honestly say that’s about the limit I would tolerate on 0-60.

Dude! Is that the Kennedale track? If so, I wish I had know you were running out there! I would have schlepped the Leaf over for a good laugh.

Yes, that was in Kennedale. That would have been great.. I put the word out on every forum I could think of that I was going to be out there, inviting other EV drivers in the area.. but nobody responded.

David, was it not possible to alternate lanes to see what that effect had on the races??

Sure, it was possible.. but I didn’t see the point and we had cameras setup to look at each other, so it would have been a pain to change.

After Jacob lost the first race, I suspect that he sabotaged the next two races by pouring water at the start line in David’s lane. 😉

Yes, rear wheel drive vs front wheel drive. Weight transfer to the rear on acceleration aids the BMW. And it’s got a real independent suspension for mountain driving.

Don’t understand Chevy’s choice of a suspension for such a Premium car like the Volt.

As for the Volt’s speed off the line, GM knows it’s customer.

When I examined the i3 rear suspension, I marveled at the complex arrangement of control arms and suspension links.

The i3 software definitely limits power from a stop and at very low speeds, presumably to avoid wheelspin with the narrow tires. It would be interesting to know how much quicker it would be to 60 if it wasn’t software/tire limited off the launch and if the Volt would still get a jump on it off the line.

The Volt power is limited at first as well. I believe the time until full torque is applied is 1.1 seconds. A GM engineer was asked about this a couple years ago and his answer kind of surprised everyone. It just seemed like the time to full torque was a lot longer than needed to protect the drive train or to limit wheel spin.

That’s true of the gen1, but not gen2.

“Missed the shift!”

“Tires were cold!”

“Forgot use my Red Key!”

“Altitude got me!”

“Left my 175/55-20 drag tires at home”

j/k’s!

I really wish GM had set the Volt 2.0 up more like the i3 in terms of acceleration – even if they had to implement an “engine assist” mode with a sport tire option like they did in the 2016 ELR. When I test drove the second gen Volt (had a gen 1), I was pretty bummed at the modest “real world” acceleration “improvement”. So often in the real work I am not just nailing it from a stop Instead it is usually from a roll, perhaps after coming around a corner (maybe behind a slower car, etc.). In short, I may be at 15, 20 or even 30 mph before hitting the pedal and by that time, the Volt is already dropping off its torque curve. Conversely, the i3 has more pull where you really need it. The i3 pulls from 30-50 23+% more quickly (per Car and Driver) and 6-16% quicker from 50-70 (depends on whether you choose to use Car and Driver’s 2016 or 2017 instrumented test results interestingly enough). Indeed, my general feeling of the Volt 2.0 was that it felt more like the gen 1.0 Volt than it did the “fun little hot hatch” impression… Read more »
Well, a lot of those so called “fun factors” are due to the RWD configuration of the i3 and light weight. Volt is a heavy pig compared to the i3 in terms of the weight (a good pig. =) Also, the i3 has more power which also helps. So, a similar comparison would be if the i3 is loaded with 3 more full size adult (in addition to the driver) and 200lbs luggage then race against the Volt with only the driver and see which one has better performance. Of course, we all know that wouldn’t fair. But the point is really weight is the biggest enemy to performance. You can always add performance by reducing weight. Volt 2.0 is slightly lighter than the Volt 1.0 but without much power increase, it is still relatively low in power for the weight. (assuming good gearing) Of course, eventually, you reached the limit of FWD setup which would add significantly more torque steering with more power added to the front wheel system. That is why the RWD setup feels more nimble in the BMW. But I imagine the Volt should handles better with its stock tires on snow than the BMW i3… Read more »

One other related note about the Gen 2 Volt performance from a stop…

In the Gen 1 Volt, they really had a lot of nanny software when accelerating from a stop. It seems they’ve done away with TOO MUCH of that in the Gen 2, so that it’s much too easy to burn rubber even when traction control is off. Conversely, on the Gen 1 Volt, that nanny software is present even regardless of the traction control setting.

IMHO, they should have fine tuned the software there so the Gen 2 Volt could have max acceleration without spinning when the traction control is on, and then let it burn rubber when traction control is turned off.

I also feel like they should have put 20 more hp in my gen 2 Volt. 😉

With a bigger battery, you would think they could easily add another 50HP…

Personally, I think the changes in the Gen 2 in terms of accelerating from a stop. The only problem with the Gen 2 is that LRR tires are CRAP for grip. It’s so bad that it really doesn’t take much effort to make the tires squeal.

Get some other non-LRR tires and you will have solved the grip issue.

I suspect that the i3 tires use a softer compound to increase grip and to make up for the decreased width.