I see a lot of hunky-looking street cars with what look like sump guards under their bumpers, F & R. I’m curious: are they really pressed steel with an aluminium-looking finish, or are they plastic lookalikes, just part of the bumper?

Plastic

My Fiat Panda has a proper 6mm steel plate jobby. On the Subaru it’s plastic.

Without seeing what your seeing we haven’t a clue.

Plastic on my Freelander. Given I never take it further off road than the odd race venue field based car park or muddy forestry lane I don’t really worry about it.
My old 90 had a proper one, tbh I only ever noticed it when it filled with snow and caused me to grind to a halt when I was out playing a few winters ago.

what is a street car?

unlikely to be a sump guard at the rear unless it’s a baja beetle or a T3 syncro

Most cars have a plastic ‘cover’ or belly ban below the engine nowadays. Think it’s to help with aerodynamics and to reduce engine noise. A few years back most VWs I saw on the motorways seemed to have them hanging half down.

what is a street car?

tsk tsk, this is how we roll on da sawf coast braap braap innit…

For instance, when doing home visits, i take this:

When lady DrP is taking the kids shopping, it’s this one:

And for family holidays we all go in this practical beauty:

DrP

i live 20yds from a speed bump and can confirm that they sound mostly plastic when people scrape them on the road at 25mph 😀

What you want is a magnesium one.

Given the popularity of plastic bash rings, I can’t really see why people are taking issue at the automotive equivalent! Anything in between tarmac/rock and your sump will help a bit.

They’re usually to encapsulate the engine for noise insulation purposes – they’re not really sump guards as such.

Except on Alfa 156’s – they used to hit the deck so regularly when the suspension bottom out that they had steel panels underneath.

They are improve fuel consumption afaik and are not to protect the sump.

what is a street car?

What is a hunky-looking street car? I’d say a small SUV or similar, probably with 4WD for those difficult parking on grass verge manouvers, much favoured for the school run.

I thought they were to stop shit being thrown up into the belt causing them to degrade.

In the case of this & many others, it is plastic or thin aluminium – its just for that ‘lets offroad’ look.