This is a summary of my recent trip to Devon. The Tl;Dr is set the charge setting to 'High' when towing!
More notes on towing with our PHEV.
We recently went on holiday from Northwest Hampshire to North Devon, a journey of approx. 150 miles via the A303, M5 and A-roads into Devon.
Going out to Devon I set the charge control to 'High'. The fuel tank was full and the battery was at 88% as we'd done some driving before we departed and didn't have time to charge. We had to make an emergency stop for fuel just short of our destination having travelled about 140 miles. There was 3% left showing in the battery.
On the run home, I left the charge setting on Auto and let the car sort things out. We set off from North Devon with a 100% charge and a nearly full tank of fuel. The route was Woolacombe to home via the M5 / A303 with a stop at Taunton Deane services at roughly halfway. The total journey distance is 140 miles give or take.
By the time we stopped at Taunton Deane, roughly 70 miles later, the battery was on 1% and we'd used about a third of the tank of fuel. We filled up there just in case, after the scare on the way down, and the calculated mileage was in the high 20's. That would have included some battery-only driving we did in Devon so I think a number in the low to mid 20's is about right for that towing leg (the onboard computer reported about 23mpg).
During this leg with battery power available, there was plenty of power for tackling the steep hills coming out of Devon onto the main road network and for acceleration. I never felt like the car was struggling, in fact, it felt more composed than my old 2l 150PS Diesel car.
For the second leg of the journey, the battery was at 0%, and would consistently exhaust the reserve held for hybrid driving, indicated by the battery icon going yellow. So for the majority of the time, we were towing purely on the 1.5l turbo petrol engine.
In this scenario, the cruise seems unable to hold a target speed. It is as if it has a cap of engine power above which it does not want to go, so it can't keep a steady 50 or 60mph. So most of the way I had the cruise off and controlled the throttle manually. The car would keep a steady speed, although up some of the larger hills coming out of Devon you had to work the engine pretty hard to do so. Forget trying to accelerate or overtake uphill just on the engine. On the flat it was fine, there was power in reserve to accelerate with and we did overtake some slower moving traffic.
On the flat, the car was automatically diverting some engine power to the battery, and downhill I took full advantage of regen. This would restore the battery icon to white, although still at 0%, and mean there was some electric power available to help with the next hill. However, on a big hill, this soon ran out leaving the ICE on its own again. It is also notable that the ACC doesn't seem to engage regen, even going downhill the power meter never indicates lower than 0%, whereas with cruise off it would be showing -15% flowing back into the battery.
I haven't had a chance to fill the car since we returned late last night, but the onboard computer was reporting 14Mpg for the trip! Having set off from Taunton Deane services with a full tank we arrived home (~85 miles) with just over 2/3rds of the thank gone. In total, I think we probably used just over a full tank for the full trip.
Compare that to the outgoing journey where I set the charge setting to 'High' and we used about the same amount of fuel and arrived with 3% of battery remaining having at no point had no electric assist available. I have to say that purely from the comfort of driving point of view this seems to be the thing to do when towing.
It seems the car has an effective range of around 140 / 150 miles when towing our 'van (1250Kg mtplm). It might be more if it were long motorway driving where there were fewer changes of speed and so less call on the battery to assist, and it'd probably be less if you were doing a lot of stop / start driving or very steep hills.
On the topic of boot space, it is a bit disappointing relative to the size of the car. It is plenty for day to day use, you'll easily get a weeks worth of shopping in there for example, but it is not as capacious as you might want when touring.
We've just had a custom bag made to the dimensions of the boot for the awning and that pretty much fills it with maybe 3/4 cm of room left above if you want to still close the boot blind. That is with a Bradcot Modul 2 air awning so no poles.
On balance I'm still happy with my purchase. It fits my requirements, I can live with the compromises when towing and for the 90% of the year when I'm not towing its perfect.