A Data Science Approach to Buying a Car

Sep 29, 2018

Choosing a car is not a quick or easy decision. For me, some of the most important factors to consider are the vehicle’s environmental impact, price, its size, and how much I like its design. Another aspect is that I like to drive vehicles on the smaller side (no trucks or SUVs for this girl). These considerations narrow my pool to a manageable depth of 23 different vehicles:

This list is mainly comprised of electric and hybrid vehicles, but I have also included the non-electric version of the Fiat 500 as well as the Mini Cooper in my list of considerations, since I think they’re really stylish. The Mini Electric isn’t available yet, but is very likely a car I will want to consider when I’m ready to make this purchase (perhaps in about two years).

There’s still a fair amount of variety here, so I’m going to need to quantify what the most important options to assess are.

The Price

Price is certainly one of the most driving factors in my decision (pun intended). No matter how amazing a car might be in every way I’d like it to be, if it’s insanely expensive, I won’t buy it. On the other hand, I hope to have a fancy new job as a Data Scientist by the time I buy this car, so while I will have a budget to adhere to, I also will allow myself the luxury of buying a new car. Thus I am only considering prices of new vehicles, not used.

As I mentioned, the Mini Electric isn’t actually available yet, so perhaps I shouldn’t keep it in the mix at this time. And the Tesla Model S is far more expensive than anything else in my list, so it’s got to hit the road as well (puns are funny, yeah?).

The Price, with Incentives

The British Columbia Clean Energy Vehicle Program offers pricing incentives for some, but not all, vehicles. Taking these incentives into consideration gives me more relevant information on how much each car will actually cost. Also, it will be nicer to view the cars with the prices ordered.

Prices range from $22,350 for the Toyota Prius c to $43,750 for the BMW i3. I’m a little surprised that the Tesla 3 isn’t the most expensive.

MPG or MPG-e

Fuel efficiency matters to the planet and to my wallet. Gas prices in BC have soared in the last year, so getting good mileage is definitely a significant objective. But how does a person compare an electric vehicle to a hybrid or a regular fuel engine? Isn’t this sort of like comparing apples and horses? As it turns out there is a miles per gallon equivalent used by the EPA, which is “a measure of the average distance traveled per unit of energy consumed” according to Wikipedia.

Clearly everything above 100mpg blows away the rest of the field, except maybe the Audi. It’s unsurprising that the regular fuel cars (the non-electric Fiat and the Mini) are at the bottom of this range, but remarkable by how much, and also that two of the three Priuses on my list are also so low here.

Range

I’ve never owned an electric car before, and I know I’m not alone in being concerned with how far the car can go on a charge (if it’s a fully electric), or on a charge and one tank of gas (if it’s a plug-in hybrid). This element is moot for the two fuel cars on my list (the Fiat 500 and the Mini Cooper), but worth exploring for all the rest.

It’s notable that the smart fortwo, while it got a high mpg-e rating, can’t go very far between charges. Most of my commuting is done within Vancouver, but I certainly want the option to take a road trip. There’s quite a range here, and I won’t seriously consider buying any vehicle that can’t go at least 100 miles.

As an aside, yes, I’m aware that I’m talking about buying this car in Canada and yet I’ve used miles for both efficiency and range, rather than kilometers. What can I tell you – I’m the one making this decision, so you’re going to have to trust that this is the best way for me to understand the data! I’m American; my brain doesn’t have to think what mpg means, but it does for km.

Size

Size is also key, and so any vehicle in a compact class or smaller is going to be more desirable than a mid-size or larger. That said, I don’t really want a 2-seater, as I worry it would be limiting in certain circumstances.

I’ll assign a points system. There are seven vehicle classes for my list of cars, some of which I consider equally desirable. Since 4 of the classes are tied for best rank, they will all get a 1, and the remaining classes get the next scores of 5, 6, and 7.

class	rank of desirability
compact, subcompact, supermini, city car	1
mid-size	5
two-seater	6
small station wagon	7

Which gives my list of cars the following points for size:

make and model	vehicle class	points for size
Audi A3 Sportback e-tron	compact	1
BMW i3	subcompact	1
Chevrolet Volt	compact	1
Fiat 500e	city car	1
Fiat 500	city car	1
Ford Focus EV	compact	1
Honda Accord Hybrid	compact	1
Mini Cooper 5-door	supermini	1
Toyota Prius	compact	1
Toyota Prius c	subcompact	1
Toyota Prius Prime	compact	1
Volkswagen e-Golf	compact	1
Honda Clarity	mid-size	5
Honda Insight	mid-size	5
Hyundai IONIQ Electric	mid-size	5
Hyundai IONIQ Electric Plus	mid-size	5
Hyundai IONIQ Hybrid	mid-size	5
Nissan LEAF	mid-size	5
Tesla Model 3	mid-size	5
smart fortwo	two-seater	6
Chevrolet Bolt	small station wagon	7

Style

Since design also factors into my decision, I’ll also assign a points system for aesthetics. 1 is again the best, and there were a few ties which are reflected in duplicate scores:

make and model	aesthetic score
Fiat 500e	1
Fiat 500	1
Mini Cooper 5-door	1
BMW i3	4
Toyota Prius	5
Toyota Prius c	5
Toyota Prius Prime	5
Nissan LEAF	8
Chevrolet Bolt	9
Chevrolet Volt	10
Hyundai IONIQ Electric	10
Hyundai IONIQ Electric Plus	10
Hyundai IONIQ Hybrid	10
Honda Accord Hybrid	14
Honda Insight	14
Ford Focus EV	16
Honda Clarity	16
smart fortwo	16
Tesla Model 3	16
Audi A3 Sportback e-tron	20
Volkswagen e-Golf	21

The Analysis

Now I need to put all these different factors together to find out which car is the best overall. In all categories the lowest rank/point score is the best; therefore the lowest overall score wins.

These different variables are all equally important to me, with the exception of mileage, so I’ll weight that a bit more heavily. Thus a final score for each car will be:

The Results

make and model	final score
Toyota Prius Prime	4.0
Hyundai IONIQ Electric Plus	6.8
Hyundai IONIQ Electric	8.4
Toyota Prius	9.8
Hyundai IONIQ Hybrid	10.2
Nissan LEAF	10.4
Toyota Prius c	10.4
Volkswagen e-Golf	10.6
Chevrolet Bolt	11.2
Fiat 500e	11.4
Chevrolet Volt	11.8
BMW i3	12.0
Tesla Model 3	12.6
smart fortwo	13.0
Honda Clarity	13.2
Honda Insight	13.2
Fiat 500	13.3
Mini Cooper 5-door	13.5
Honda Accord Hybrid	13.6
Ford Focus EV	14.8
Audi A3 Sportback e-tron	15.0

make and model	vehicle class	mpg or mpge equivalent	price after incentives	final score
Toyota Prius Prime	compact	133	30490	4

The Toyota Prius Prime is the clear winner here. It’s a little more than $30k, gets outstanding mileage and range, is compact and cute to boot. It’s final score came in at 4 points, ahead of the runner-up Hyundai IONIQ Electric Plus with 6.8 points. Prices may change in the future, but if I were to buy this car today, the Prius Prime is the best choice.

Rachel K. Riggs

Data Scientist

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and solutions

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