The process of car cleaning is far more complex but effective than it used to be, and finding the best prewash is the perfect example of this. Pre-soaking a car with chemicals before you shampoo is an important step for dislodging muck and grime.
Pre-wash is excellent. You spray it on, then wash it off. It's not quite as fancy-looking as a good snow foam, but it'll help remove grease and dislodge embedded deposits without being a cocktail of abrasive cocktails that can dull your paint over time (like a traffic film remover).
If you've consumed at least one or two therapeutic car detailing videos, you'll notice that professionals use pre-wash before the therapeutic snow foam to lift off the thickest and grimiest of dirt. While you won't find us on TikTok, we decided to organise the ultimate pre-wash test of our own: remove years of moss, dirt, and algae from a 1982 Audi 80 CD. A rare five-cylinder version that, at the time of writing, hasn't been taxed since 1996.
The best car prewash tested 2025 at a glance:
We took each product and applied it panel-by-panel before judging the effects. We then took our favourite pre-wash and proceeded with it to cover the remaining bits of the car before giving it a full wash and detail with our various car cleaning kit products. Needless to say, it looked like a different car once completed.
What we look for in car prewash
Primarily, we're looking for good performance when it comes to prewash. Getting all the deep dirt and grime off a vehicle is everybody's wish when they're purchasing a cleaning product. One aspect that ties into that is features - this can mean anything from how it's designed to work on a number of different surfaces to how versatile it is in its application.
It is easy to chew through prewash bottles when you use them for a deep clean, so value for money is also key. If you're a keen car detailer, you'll be getting through a lot of prewash, so cost-effectiveness is a real bonus in this group test. All of these will eventually tie into our overall score, which determines how much we recommend the product.
The best car prewash 2025
The best prewash for cars
CARAs pre-washes go, few come close to the sheer grime-removing power of this product from Car Gods. A few sprays over the thick dirt, and gone was the filth that plagued the even greener Audi.
It boasts pretty good value for the quantity you get, is safe to use on a number of surfaces from plastic to metal and even carbon fibre. It's great for removing loose dirt, bug deposits, and other detritus on the paintwork. If you're on the market for a pre-wash to enhance your inner detailer on the best level, you really should be getting an order in for one of these.
Pros
- Pretty good value for money
- Effortlessly removed the worst dirt and grime on our test subject
- You get a decent amount of quantity
Cons
- Be careful not to spray too much at once
- Can leave streaks if you don't rinse straight away
| Volume | 1L |
| Suitable for | All exterior surfaces |
| Curing time | Five minutes |
| Application type | Spray-on |
A premium prewash that's designed to shift more embedded bits of dirt, this is the Bug and Grime Remover from Auto Finesse. Safe on waxes and sealant, this spray is effective at removing embedded dirt and grime and can even be used to degrease engine bays.
We used this one to clean the almost-black fuel filler cap of the Audi as well as the rear quarter panel, after two sprays and a rinse, it was clear as day and it felt safe to touch. It represents good value, too. It's one of the cheapest products on our test, and it impressed massively.
Pros
- Powerful cleaner that won't strip protectants
- Quite good value
- Great for cleaning fuel doors
Cons
- Takes a few sprays to get every last bit
| Volume | 1L |
| Suitable for | Exterior surfaces and engine bays |
| Curing time | Several minutes |
| Application | Spray-on |
The best prewash on a budget
Via ValetProThis is a concentrated prewash, which makes it a really good value option, as one litre will make eight litres of prewash (at an 8:1 dilution ratio). Dilute it into a spray bottle with water and spray it onto your car as you would with any other prewash. We did so on our test and we were pleasantly surprised at how much dirt it managed to lift off. This prewash is alkaline-based (9.5 pH value) to help remove insect and road grime and is infused with orange oil to naturally enhance its cleaning power. Like most other prewashes, it's safe to use on wax and sealants too.
It's a shame it's not pH neutral, so it can be used on everything, but it dealt with a lot, considering how filthy that Audi was.
Pros
- Very affordable
- Very capable for its price point
- Very efficient when in use
Cons
- Not biodegradable
- Isn't quite as powerful on the toughest of grime
| Volume | 1L |
| Suitable for | Bodywork and wheels |
| Curing time | Several minutes |
| Application | Diluted 1:8 |
The best pre-wash for diluting
CARwww.ebay.co.uk
Some pre-washes need diluting. This simply means you pour a small portion into a measuring bottle before mixing with water. Duel Autocare's Nitty Gritty is one of them, and we poured a bit into the Autoglym Easy Sprayer. The results were pretty impressive.
Granted, the bonnet and roof are arguably the worst parts of a dirty car and possibly the hardest to clean since the most amount of elements hit them. But the Nitty Gritty dealt with the dirt really very well. It's just as good that the product is efficient because you don't get an awful lot at a 500ml capacity. You did, however, have to agitate loads of it in order for it to work, and it just wasn't quite as effortless as the Car Gods and Auto Finesse products.
Pros
- Very effective in a spray bottle (when diluted)
- Most efficient to use out of the lot
- Cuts through thick dirt pretty well
Cons
- Doesn't quite do the job as well as the others
- Panels needed going over a few times
| Volume | 500ml |
| Suitable for | Bodywork, engine bay, wheels, arches |
| Curing time | 2-3 minutes |
| Application type | Spray-on or diluted |
Best all-purpose cleaner
CARAll-purpose cleaners (APCs) are never as strong as dedicated pre-washes, but Autoglym say you can use this APC to 'pre-soak' a car before getting on with the full wash. So with that in mind, we decided to give it a try.
Unfortunately, despite a few sprays, it didn't quite impress as much as the other products tested. It felt weaker, less capable, and as if the Audi was a little too much for it. It's fair to suggest that a seriously mucky car is too much for any pre-wash, but the others did the job just fine, and the Autoglym APC let the side down slightly. With that said, it is a versatile product if you want to clean up other areas of the car, including the interior. That is something the others can't match.
Pros
- Very versatile
- Reasonably good value
- Perfect for quick sprucing
Cons
- No good on very filthy cars
- Easy to get through bottle
| Volume | 1L |
| Suitable for | All vehicle surfaces, inside and out |
| Curing time | None |
| Application | Spray-on |
Our quirky companion of the pre-wash group test came in the form of the Autoglym Easy Sprayer. It's designed to take a diluted sample of cleaning product with water before being equally sprayed along the panel of a car. We weren't expecting too much, but it exceeded our initial thoughts.
You have to pump it several times before spraying, but after enough pumps, you get a paint gun-like application for about 15 seconds. No spray is wasted and you get a decent amount on each panel without using too much. It's a clever tool that really makes application of pre-wash and other things much easier than straining your fingertips with repetitive spray bottles.
Pros
- Durable item with great build quality
- Amazingly effective sprayer
- Works with all sorts of cleaning products
Cons
- You do have to keep pumping it for longer jobs
- It's hard to say it represents good value
| Capacity | 1L |
| Suitable for | Lots of cleaning tasks |
| Application type | Spray-on |
What you need to know about prewash
What is car prewash?
It's difficult to pinpoint exactly what prewash is. It's an umbrella term applied to pretty much any product you apply before the shampooing stage. This includes snow foam, all-purpose cleaner , insect and grime remover and traffic film remover. The purpose is that it removes the worst/top layer of dirt and grime before you can proceed with the rest. Detailers use it pretty religiously as well as some prewash integrated snow foams.
For this test, we simply took what could be easily diluted and/or sprayed on in order to see if they were any good at removing neglected car dirt. For each product, we agitated the prewash using a soft detailing brush and spread it evenly across each panel. We're talking about a car that can almost be described as 'barn find' condition, so the products had a lot on their shoulders.
Does car prewash work?
Yes, it absolutely works. Prewash is designed to lift up the top layer of dirt from your car's paintwork, which, in the Audi test car's case, consisted of some very deep grime and algae. We've tried a selection of them and found each prewash to work very amicably at the intended task.
Prewash is also safer for your paintwork. Lifting up the top layer of dirt before rinsing it off with a hose or pressure washer reduces any risk of little bits of dirt and grit scratching the paint. If you were to apply shampoo alone, that risk is slightly higher. But above all, prewash contributes to a car getting as clean as it can possibly get, as using it simply agitates more dirt off than the sole use of shampoo.
What is the best car prewash?
As our findings would suggest, we highly recommend Car Gods Almighty Prewash. It worked the hardest at getting years of algae off the classic Audi and made washing it with shampoo a breeze thereafter. Granted, this is an extreme test bed to be experimenting these different products on, but in the process of restoring a bit of shine back to a car's paintwork, it was the best performer.
How is prewash different to snow foam?
Prewash is usually added to the name of most snow foams because you use it before washing your car properly with mitts. However proper prewash is different and it's worth knowing what that is. Whereas snow foam is a thick white foam, prewash is translucent. Furthermore, snow foam is at its best when agitating pre-wash. This is so you can agitate it in a contactless way - thus reducing any chances of light scratches.
Snow foam also requires a pressure washer and foam lance to work whereas prewash can be sprayed on from the bottle. We've listed our favourite snow foams here, where again, we tested each one panel-by-panel on a brand new Range Rover Sport before measuring the effects.
How we tested the prewash
As briefly mentioned throughout our guide, the challenge was to remove years of dirt, grime, algae and whatever else off a non-running 1982 Audi 80 CD. It had accumulated so much filth, that any standard shampoo wouldn't have gotten to the clean layer of paint hiding beneath.
We applied the different prewash products panel by panel and judged the cleanliness of them from there. We then rinsed the prewash using a Worx WG633E Nitro Hydroshot pressure washer (56 Bar) and gave the car a final clean using Autoglym's newly-introduced ceramic shampoo and Bilt Hamber's Auto-Wash.
Who tested the prewash?
This test was conducted by Aaron Hussain. As a classic car owner who is fastidious about using the right products on them, the Audi test subject was an ideal platform for him. With slightly more delicate paint and trim to deal with, he knew that being careful was key in this test.
Aaron Hussain is a commercial content writer at Bauer Media writing for Parkers and CAR. He is obsessed with classic cars and anything with a fascinating story to tell.