My personal car efficiency analysis

My first car was a hybrid, a 2009 2nd gen Toyota Prius, for it’s time it was meant to be well efficient and minimal, chiefly a Tesla style but tiny touchscreen controlled everything, since then i owned a few other cars and test drove a lot ef EVs but i always felt like there is more to efficiency than MPG or miles per kWh so here is my attempt to quantify it.

The Efficiency metric i created with is factoring everything but the acceleration in the chart above and matches my real life experience of these cars.

I owned all the ones that are not greyed and i always felt that there is something to be said for how nimble some felt like the Priuses especially if you take their combustion engine component out of the question, for the 3 months that i owned the 2020 plugin Prius i ran it in EV mode 90% of the time and it felt very lean, i was getting up to the 4 miles per kWh advertised.

The Mercedeses (2006 ML350 and 2015 B250e) were both very smooth even for their size, refined as the engineering in those cars might be little mind was paid to how much running them will cost, they felt like they were built to last 100 years but that is a bit of a waste as well to be honest.

The ML350 was a leather and wood panelled tank that still managed to drive smoothly and quietly but it had so much bulk the sheer mass combined with the low drag coefficient made it feel the least efficient of everything i ever drove.

The B250e Tesla powered frankenstein took a solid car as a platform and added great battery and motor technology from Tesla but in pairing them compromised essentials like fast charging and range, the two together made the car unusable for anything else than grocery shopping in winter and in the summers there are only so manny coffee brakes and walks you can take as you had to charge 1 hour for each hour you drive, basically Mercedes did not really want this car to succeed and while the aerodynamics were not too bad for a small SUV the overall efficiency at only around 2 miles per kWh made the already small battery feel even smaller.

Moving on to the DS3 which is my current daily driver, a well balanced light crossover, bit flimsy in places and bit lacking in software is nevertheless a very pleasant surprise and a solid EV with up to 100 kWh fast charging and almost 200 mile range in summers, the drag coefficient is not great and you don’t get a lot of internal space for it either but it still manages at least 3 miles per kWh in the winter even closing up to 4 in the summers which is testament to ints lightness in the face of lacking aerodynamics, the whole front grille is shared with a petrol counterpart and does not make the most of what other EV’s take advantage of.

The weight of the DS is very close to the more aerodynamic plugin Prius that makes use of all kinds of weight saving tricks like carbon fibre boot lid only goes to show how good that Prius could be with no hybrid engine and just a light battery and electric motor but of course Toyota has no interest in doing that because it would be too good and show them out for the dinosaurs they really are clenching to petrol for as long as they can.

I am guessing that Prius Prime made full electric and with solar panels would be close to the Lightyear One which is the car that i admire most and i included here as the golden standard for efficiency even if i did not have the privilege of being able to test drive one.

I’ve included the Tesla and Porsche for comparison since i test drove both, compared to the Lightyear which has a 170 Wh/kg figure (60kWh in a 350kg battery pack) the Taycan has a battery pack energy density of only 148 Wh/kg and the Model Y 141 Wh/kg (75 kWh in a 530 kg battery pack) soon to improve to 182 Wh/kg (with the new structural pack of 4680 cells), until that happens both the Tesla and the Porsche are way too bulky even with their decent aerodynamics to rate too hight on my efficiency scale, its the updated generations of both that hopefully will tip the scales.

Driving them of the flat they seem almost identical in blazing fast acceleration, its in the corners and roundabouts that the Taycan shows its agility but its still a very large bulky machine that could benefit from some weight saving and minimalism like the Tesla (it weights more that the Model Y SUV), the Taycan for example has two charging ports on each side instead of combining AC and CCS into one port, its a example of the lack of leanness present throughout especially since you can’t use both charging points at the same time which raises a few questions about their existence.

I have not drove or cared to include early whales like the Audi E-tron or Mercedes EQC because of their embarrassing inefficiencies, those cars weight 500 kg more than anything else in this list with numbers like 123 Wh/kg on the Mercedes battery pack and only 2.5 miles per kWh.