Seriously, its not like any real life
net down hill journey is going to be a no brakes run straight down the mountain side. If that were the case then I could just jump in a billy cart and ride it down the mountain (you can't, you're not getting down the Blue Mountains in a billy cart, not in one piece). You've driven through a mountain range before right? Any normal journey through mountainous regions especially like the Blue Mountains is lots and lots of winding roads up and down the side of the mountain until you get to the coast. Here, let's do some math on a hypothetical situation since everyone is so enthused by the idea of it:
ICE car and EV both start off with same amount of range R_ICE=R_EV= 20km.
Let's start them off down a 10km section of road that's all down hill. You can't just freewheel it down the whole way, you need to brake to stay at a sensible speed and take turns. The ICE car can just engine brake the whole way and thus not use any fuel, it's range remains the same. The EV uses regen braking instead. Let's be conservative, give the ICE car an easy game and say the EV recovers range equal to only 10% (
literature reports 16% to 70%) so it gains 1km range.
R_ICE=20km
R_EV=21km
Since they're both "equally efficient" and we're directly comparing them directly based on a "range" energy consumption and capacity they both drive up an equal grade section for 10 km and both use up 10km of range.
R_ICE=10km
R_EV=11km
Then another equal grade down hill section for 20km this time
R_ICE=10km
R_EV=13km
up 5km again
R_ICE=5km
R_EV=8km
Down 20km again
R_ICE=5km
R_EV=10km
up 5km again
R_ICE=0km
R_EV=5km
The ICE makes it to the crest and starts rolling down to the next section but has no fuel. Onto the next section down for 10km
R_ICE=0km
R_EV=6km
Almost at the end and there's a 1km uphill section. The ICE car is out of fuel and can't go up but the EV still has range.
R_ICE=Dead 1km back
R_EV=5km
Then the last 10km of the trip down hill.
R_ICE=Dead 11km back
R_EV=Made it with 6km spare
Let's recap that journey. Both cars drove along the same undulating mountain road consistent of equally graded up and down section with a net downhill run. In total 10+10+20+5+20+5+10+1+10=91 km, with an uphill total of 10+5+5+1=21 km and a downhill total of 10+20+20+10+10=70 km. The EV car despite its terrible regen braking manged to recover some of the gravitation potential energy and made the 91km journey with 6km to spare despite starting with 20km of "range". The ICE car also manged to go quite far starting with the same 20km of "range" but got left behind 11km back when it was out of fuel and couldn't climb a short up hill section. In the end the EV made it with range to spare but the ICE car didn't. You can twist this anyway you want. Change the scales of length, change the regen efficiency, change the proportions uphill and downhill, even make the whole thing downhill, the result will be the same: the EV will go the furthest with the most range left over.
The point is: ICE cars have no regen, at all. EVs have regen. In any situation beyond just a hypothetical, unrealistic, race track run with no braking. The EV is coming out on top. There is no question or uncertainty about it. EVs have regen. ICE cars don't have regen. EVs are unequivocally more efficient.
The advantage of ICE cars is, despite their terrible efficiency, they have higher energy capacity because fossilised, refined plankton juice is much higher energy density than li ion batteries. The problem there is EVs as they are have more than enough range for everyone apart from people that need to cover a domestic flight level of distance while barely stopping e.g. truckies.
This really is a 'problem' which needs a properly defined set of conditions and math to solve. In the end math talks; everything else walks.
Well here's the talk. I guess you should walk
And since the ICE car is likely to be lighter the resistance of the tyres will be less.
Hyundai Elantra:
-Kerb Weight: 1420 kg
-Length:4620 mm
-Width:1800 mm
Hyundai Ioniq Electric:
-Kerb Weight: 1575 kg
-Length: 4470 mm
-Width: 1820 mm
Hyundai Ioniq Hybrid:
-Kerb Weight: 1467 kg
-Length: 4470 mm
-Width: 1820 mm
So 1575/1420=1.109. So 11% more weight at most for a comparable car? That's gonna cause rolling resistance increase that out weighs any energy recovery?