A great many of them are only cosmetic. Take a close look at the grilles for, for example, a late model Ford Explorer, or a Jeep Cherokee. The bottom half or less of what's visible as a grille, is actually open. It's better for aero for the actual opening to be down low to the ground, with the upper part being cosmetic, and no bigger than necessary.

As for the styling trend ... there seems to have been a competition among pickup-truck and SUV manufacturers the last quite a few years, to have the largest possible grille and the most area of chrome with the highest possible hood (at the expense of forward-up-close visibility, and probably aero). Lexus and Toyota are offenders, too. And BMW's twin-kidneys have been getting bigger and bigger.

I don't care for this trend. Personally, I like that my Chevy Bolt (styling-refresh model) has no front grille. Well, that's not quite true, although what it has is pretty subtle. There's a small slot down low to let in the small amount of cooling air that it needs, and it has active grille shutters in front of that, to block this opening off when not needed. As far as I can tell, a little electric pump circulates coolant through that radiator and the powertrain bits that need cooling all the time, and in lieu of a thermostat in this cooling loop, it uses the active grill shutters to regulate the temp in the cooling loop. The air-con condenser is also up there, but I'm thinking that whenever the air-con is on, it probably also could use cooling for the powertrain.

I've opened the hood after driving for some time just to see what's going on, and never felt anything that I could reach being much above ambient.

The trend for a high front is at least in part the pedestrian crash regs, to provide lots of crumple room above the engine.

Cheers

Greg Locock


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And yet, most cars designed for sale in Europe (where the pedestrian-impact rules are in force) have low bumpers and sloping hoods, in the interest of striking a pedestrian in the lower legs first and then cushioning the impact with the hood by having clearance between the hood and whatever's underneath it.

The US-market pickup truck high front ends will just give blunt-force trauma over the pedestrian's entire body.

Even in Europe, I don't think the pedestrian-impact regs are applicable to heavier vehicles intended for commercial use.

Quote:

Nowadays passenger car aerodynamics is an important part of fuel economy gains.

From a functional standpoint yes but from a regulatory one no. Fuel economy and emission regs for ~20 years have factored frontal area and its easier/cheaper to certify a brick than an arrow so that is what the public gets.

CAFE in USA has "footprint" (wheelbase x track width) as one of the factors in its requirements (which are insanely complex). This is an incentive to make physically bigger trucks, but it is not an incentive to make any vehicle of a given size have poor aero instead of good aero. Also, anything >8500lb GVWR is exempt from CAFE, and that's an incentive to make a heavier truck, but not a less-aerodynamic one. The manufacturers have put a decent amount of effort into improving aerodynamics, but it's countered by customers wanting the biggest and toughest-looking thing that they can find. The marketing push to have the highest possible tow ratings also pushes the balance towards having the biggest possible flow through the radiators, which is bad for aero, which is a disbenefit to those same consumers all the time even if they only come anywhere near the towing limits a microscopic percentage of the time.

Active grill shutters help a little. Lots (all?) of the new pickup trucks have an air-dam below the front bumper to encourage air to go around rather than underneath.

I don't think most people seriously consider fuel economy when buying a pickup; easily 90% of pickups on the road are single-occupant and by the looks of them, most of those vehicles have never carried or towed anything more than groceries.

TTFN (ta ta for now)
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Grills. Large Grills.

Misread the title. :)

Tmoose (Mechanical)
I agree. Like one particular brand that has had one of the most non appealing designed grills for I think now a decade plus. Even if they are closed for air passage the multi louvers would still offer some
resistance I would think. Strange how the EV's seem to not consider that as an important styling issue.