One of the many cons being perpetrated upon the car-buying public is that the very small, very turbocharged four cylinder engines being served up as replacements for “thirsty” V6 and even V8 engines in larger vehicles especially are money-savers.
Hell, they hardly save much gas.
And they cost in other – hidden – ways.
Consider, as an example of the trend, the stats of the 2019 Subaru Ascent vs. those of the Chevy Tahoe. The former is representative of the New School while the Chevy is as Old School as it gets in anything new.
Both are big – and heavy – vehicles. Each seat up to eight people in three rows. But the Ascent – which is a car-based crossover SUV – has a very small-for-its-size engine, just 2.4 liters and 260 hp to haul around its 4,430 lbs. (that’s empty, before even the driver climbs on board). The EPA says it gets 20 city, 26 highway – best case. Amazon.com Gift Card i... Buy New $15.00 (as of 07:25 EDT - Details)
I have been test-driving this vehicle for several days and am averaging 22.8 MPG, according to the car’s computer.
The Tahoe is also a big vehicle and a much heavier vehicle – by more than 1,000 lbs. Because it’s a truck-based SUV, with a heavier-duty frame and truck-type 4WD gear (including a two-speed transfer case) vs. the Subaru’s lighter-duty all-wheel-drive system. Unlike the Soobie, the Chevy has a big V8 under its hood – 5.3 liters and 355 horsepower, which is more than twice the size of the Subaru’s engine and almost 100 hp stronger.
And yet, it hardly uses much more gas.
The EPA says 16 city, 23 highway – which amounts to a difference without much distinction of just 4 MPG in city driving and 3 MPG on the highway. I’ve driven several new Tahoes over the years and they also average about what the Soobie averages.
But the Chevy is much stronger, much more capable vehicle. For example, it can tow 8,400 lbs. vs. several thousand pounds less for the Subaru.
And much quicker, too.
Zero to 60 in just 5.8 seconds vs. 7.3 seconds for the lighter, smaller-engined, but not-much-smaller Subaru (which is about 197 inches long overall vs. 204 inches for the Tahoe).
So, what’s the upside to the Subaru’s downsized engine? It is hard to figure.
And it is not just Subaru.
It is becoming practice to put undersized engines in overisized vehicles. Mazda, for example, sells a vehicle that is a direct apples-to-apples cross shop of the Ascent, the CX-9. It is also a large, car-based crossover SUV with three rows of seats . . . and a very small (2.5 liters) engine under its hood.
It also rates 20 city, 26 highway according to the EPA – like its Subaru rival.
Now, vehicles like the Ascent and the CX-9 never came with V8s; that would be over-engining them. But they did used to come with size-appropriate V6 engines and – shocking, as Geraldo used to say all the time – they didn’t use much more fuel, either. Amazon.com $25 Gift Ca... Buy New $25.00 (as of 02:45 EDT - Details)
For example, the 2015 Mazda CX-9, which was available with a 3.7 liter V6, rated 17 city, 24 highway – a difference of 3 MPG in city driving and just 2 MPG on the highway. It’s such a small difference as to make no meaningful difference – in terms of what you paid for gas.
Today you pay in other ways.
Power/performance is one way.
The CX-9’s no-longer-available 3.7 liter V6 was much stronger than the turbo 2.5 liter four which replaced it – 273 hp then vs. 225 hp now, a difference of almost 50 hp, which is a difference with a distinction.
Another is stress – and expense.
Undersized engines rely on turbo boost as the replacement for displacement. The theory is that you’ll use less gas when the engine isn’t being turbo-boosted. Which is fine – and true – when the engine is idling and the car isn’t moving.