Our hybrid’s use of battery cells is testing our brain cells
9 October 2017

Interesting car, this. Interesting and complicated. You might recall that in my previous report I was scratching my head over how to accurately determine the Passat’s real-world economy.

We all know that official economy figures are to be taken with a pinch of salt. Or are they? VW claims 156.9mpg combined for the Passat GTE, which sounds real-world laughable, but I’ve already seen over 100mpg on the trip meter on my 36-mile, mostly motorway, part-urban commute. 

The other day I did a five-mile local run almost entirely on battery power. The petrol engine chimed in of its own accord (I’m still not sure why) for barely half a minute, if that, so the trip meter calculated an average economy figure based on the amount of fuel used over the whole journey. 

The result? It says we managed 237mpg. Except, of course, we didn’t, because if that were so the Passat’s 50-litre tank would have a 2610-mile range, which it doesn’t – unless all of your journeys are very short and your battery charges are regular. (Incidentally, I brimmed the tank with the trip meter telling me I had about 20 miles of petrol range left and it took 50.69 litres.) 

To cloud the issue further, VW claims a ‘total driving range’ of 664 miles, including 31 miles on electric power. If we subtract 31 from 664 and then divide the answer by the fuel tank capacity in gallons (11 of them), we get 57.5mpg. To be fair to VW, that’s a tacit acknowledgment that the official figure of 156.9mpg isn’t to be taken too seriously. But how is that figure measured? I don’t know. 

For the time being, I’m going by what the trip meter claims is the car’s overall average economy, which is currently 64.5mpg (past experience tells me that VW Group trip meters aren’t too wide of the mark). I promise not to go on about fuel economy in my next report. 

It took 1374 miles for me to realise I could toggle between the Passat GTE’s power sources with repeated presses of the E-Mode button next to the gear lever, rather than pressing it once, then selecting E-Mode or Hybrid via the touchscreen. What’s that you say? RTFM? No idea what you’re talking about. TIM DICKSON 

VOLKSWAGEN PASSAT GTE ADVANCE DSG ESTATE

Price £39,770 (after £2500 gov’t grant) Price as tested £42,360 (after grant) Options Driver’s Assistance Pack Plus (including emergency assist intervention, dynamic light assist, lane assist, predictive pedestrian protection and traffic jam assist) £1225, Dynamic Chassis Control £725, metallic paint £595, rubber boot mat £45 Economy 60.9mpg Faults None Expenses None

PREVIOUS REPORTS:

We’re all for diversity around here. Among the current 30-odd cars on the fleet, we have a V-twin three-wheeler, a petrol V8, a tri-turbo diesel V8, a petrol W12, an EV, a parallel hybrid, two hydrogen fuel cell cars, a petrol-electric sports car and now this, the plug-in hybrid Volkswagen Passat GTE Estate.

Those last six cars are interesting because they represent a disproportionate 20% of Autocar’s long-termer lineup – disproportionate because for now the real-world percentage of alternatively fuelled vehicles on our nation’s roads is much lower.

Diversity, then, and pioneering the future of motoring – whatever that may turn out to be. And I suppose it’s worth asking if that future is going to be one in which the plug-in hybrid prevails, and it’s a question to which I hope to find an answer or, more likely, several answers, depending on your point of view. I already have a feeling, you see, that this car is going to cause some head-scratching.

We’re pretty well acquainted with the Passat GTE. We’ve already road tested it, albeit in saloon guise, and subjected it, as an estate, to a comparison test, and the car has scored a solid four stars on each occasion. This Passat uses the Volkswagen Group’s increasingly familiar petrol-electric set-up of a 1.4 TSI petrol engine, here making 154bhp, mated to a 113bhp electric motor and driving through a six-speed dual-clutch automatic gearbox. It’s good for 0-62mph in a claimed 7.6sec, which isn’t exactly slow.

The electric motor is powered by a 9.9kWh battery, which takes about two and half hours to fully charge via a wall box charger (at the office) or four and a half hours via a three-pin domestic plug (at my house). The battery lives under the rear seats and reduces fuel tank capacity from the 66 litres of a regular Passat to 50 litres.

You can have your Passat GTE in regular form, which comes quite well equipped, or in Advance trim, which is much more generous. We’ve gone for Advance, which includes VW’s Discover Navigation Pro with an 8.0in touchscreen, adaptive cruise control, emergency braking, a panoramic sunroof and a fully configurable 12.3in-wide TFT instrument display. To that, we’ve added metallic paint, Dynamic Chassis Control (DCC, or switchable suspension settings to you and me) and the tech-tastic Driver’s Assistance Pack. We’ve also got ‘St Tropez’ leather trim.

All of that means our car costs a hefty £44,860 before the government’s £2500 grant for plug-in cars. Even without the extras, an Advance-spec Passat GTE Estate costs in excess of £41k, which potential buyers will have to bear in mind given that it puts the car in the firing line of the impending new VED rules for cars costing £40,000 and above, due next month.

That running-cost can of worms aside, the Passat is living up to my earlier suspicions and posing as many questions as it is answering them. Why, for example, does the petrol engine sometimes come on when I don’t want it to, even at low speeds, in far from freezing temperatures, with a full battery and no air-con, heated seats or anything else switched on? Is there, meanwhile, a way of finding out the Passat’s total mileage on electric power for any given journey if I’m switching between power sources? Among all of the other information – and there’s a lot of it – that nugget isn’t in there.

But the thing that’s bugging me, and possibly you, the most is this: how economical is it? Specifically, how do I work out an accurate miles per gallon figure for the petrol engine? With any given journey being a mix of petrol and electric power, the traditional brim-to-brim calculation is corrupted by the fact that for some of the distance travelled no petrol was used.

So on my 36-mile each-way commute, with a battery refill at each end, I’ve already been recording some pretty impressive figures – at least according to the trip meter. But the longer the journey (assuming it’s non-stop), the less impressive the average economy figure for that journey, because the petrol engine does proportionally more of the work as the miles go up.

I could, of course, just drive around with an empty battery and work out the fuel economy that way, but to do so would utterly miss the point of having a hybrid powertrain in the first place and in no way reflect how I use the car.

In the meantime, I’m relying on the trip meter’s claimed overall average figure, which right now is 60.9mpg. That’s reasonably impressive, but all of my journeys so far have had some sort of electrical assistance, and I’m trying hard to optimise the free (or at least significantly cheaper) propulsion to best effect, which I’ve been doing by using electric power to get up to speed and then switching to petrol once I’m maintaining a relatively constant velocity.

If nothing else, I’m going to have a lot to write about in terms of economy, efficiency and running costs. You’ll have to stop me if it gets boring (if you’re not there already). Still, this is a big, practical car with a huge boot and lots of kit, so I’ll be finding out how useful and usable much or all of that is. Stand by to be riveted.

VOLKSWAGEN PASSAT GTE ADVANCE DSG ESTATE

Price £39,770 (after £2500 gov’t grant) Price as tested £42,360 (after grant) Options Driver’s Assistance Pack Plus (including emergency assist intervention, dynamic light assist, lane assist, predictive pedestrian protection and traffic jam assist) £1225, Dynamic Chassis Control £725, metallic paint £595, rubber boot mat £45 Economy 60.9mpg Faults None Expenses None

Our Verdict

Volkswagen treats the Passat to a plug-in hybrid makeover

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Comments
24

3 August 2017

Autocar's test fleet is so diverse that you may be in danger of loosing touch with mainstream cars. I hope that there is a base model Ford Focus or Vauxhall Astra (of thye type which most people drive) to maintain a point of reference? 

Regarding the Passat hybrid, could the unexpected petrol engine start ups be explained by the need to maintain a decent working temperature, so that when it is actually needed it is always warmed up and ready to go? 

Incidentally I don't think that VW's choice of having both a powerful petrol engine and a similarly powerful electric motor is the way to go. The net result is a car (like the Vauxhall Ampera) which is excessively heavy, powerful and expensive, since it is effectively twin-engined. Far more promising (in my view) is the mild hybrid - petrol  engine with light electric assistance - or the range extender hybrid (BMW i3) using a simple light petrol engine to give added range to an EV. Incidentally no weight figure is quoted for the Passat. I bet it's very heavy!

3 August 2017

The engine should really be a small highly tuned 3 cylinder, ideally diesel too.

3 August 2017

Clearly the performance of the hybrid petol/electric engines will take centre stage in the car's reviews, but maybe in the follow up reports some info on how well the car drives, i.e rides, handles, steers, brakes, chanrges gear, its refinment levels etc. could be included too.

3 August 2017

So, the trade off is that you lose 16 litres of fuel, so 160 miles range (calculated at 10 miles/litre or 45mpg) for 23-30 miles by battery. A net range loss of 130 miles.

Doesn't feel much like a "win" to me

3 August 2017

"In the meantime, I’m relying on the trip meter’s claimed overall average figure, which right now is 60.9mpg."

You can knock about 10% off that figure then, as my experience with a 2017 vw trip computer compared to actual physical topping up calculations. Maybe Autocar can look into how accurate car fuel computers actually are, as in my opinion, seeing as we're talking about a device that should be able to monitor fuel flow and therefore total amounts used pretty accurately, a 10% inaccurate reading isn't really acceptable in 2017. Of course, it could be argued that manufacturers purposely do this to make their vehicles appear to be more fuel efficient than they actually are !!!

3 August 2017

My recent experience of a couple of Hyundai / Kia producs show trip computer mpg errors of  between 5 and 10% optimistic, so maybe this is standard through the industry? It's certainly not good enough. The fuel needs to be metered out with an accuracy of better than 1% for emissions purposes, so why can't we have a display of similar accuracy?  

As for motoring publications, they need to get back to basics and start making proper brim-to-brim measurents with a corrected odometer. 

3 August 2017
LP in Brighton wrote:

My recent experience of a couple of Hyundai / Kia producs show trip computer mpg errors of  between 5 and 10% optimistic, so maybe this is standard through the industry? It's certainly not good enough. The fuel needs to be metered out with an accuracy of better than 1% for emissions purposes, so why can't we have a display of similar accuracy?  

As for motoring publications, they need to get back to basics and start making proper brim-to-brim measurents with a corrected odometer. 

Agreed, my Astra trip computer claims 70.3mpg for its entire life thus far (34k miles), whilst the reality (by logging all my fill ups)  is 62.2 - 13% over optimistic. If the trip was accurate I'd be more than happy with the mpg, but instead I feel mildly annoyed that my car endlessly lies to me!

The trip computer on the 1series I had previously was accurate to 3%, so it can be done! 

3 August 2017

Absurd amount of money for something that is meant to be a family estate car - who would pay that??

PMG

3 August 2017

Is not the only way to produce a sense of the cost of running such a vehicle to report average total cost in pence per mile being total cost of petrol plus total cost of electricity divided by mileage?

I would be very interested in Autocar producing such figures across all vehicles petrol, diesel, all types of hybrid plus pure EVs. It would be very interesting for this particular vehicle.

PMG Sussex

3 August 2017
PMG wrote:

Is not the only way to produce a sense of the cost of running such a vehicle to report average total cost in pence per mile being total cost of petrol plus total cost of electricity divided by mileage?

I would be very interested in Autocar producing such figures across all vehicles petrol, diesel, all types of hybrid plus pure EVs. It would be very interesting for this particular vehicle.

 

That would introduce the cost of fuel and elctricity into the equation, which given the differences in fuel costs from petrol station to petrol station and the myriad of electricity tariffs available, would be incomparible across the board. You need to know the amount of fuel put into the vehicle, ie the total volume of petrol/diesel and the total amount of electricity in kW. and leave the price per kWh and per litre  to be added by the individual, or pick typical prices and apply them to all vehicles tested.

The split of electricity to petrol also needs to be considered, each vehicle has a limited fuel tank capacity and limited battery capacity, although a battery could be filled many times more frequently than the fuel tank.

There must be a way of creating a standard model to allow comparison model to model, but as we know standard models aren't representative of the real world!..

 

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