Well, it has been a difficult effort - much more than anticipated. Without further ado, here's my thoughts on diecast vics in wargaming...
First it is unusual to find a line of cars that are actually all the same scale. What the manufacturer does is say "1:43" and many of the cars are. But all the cars are the same SIZE, which is to say about the same dimensions. So a Mini or Fiat 500 will be about the same size as a full-size truck, which means it is NOT the same scale as it should be much smaller if it was actually 1:43. This is a common problem with nearly all the popular lines, and has to do with the manufacturing process no doubt.
So, right off the bat you have a problem - the scales of cars in the same line by same company do not actually match up, only the sizes do. This means you have to shop around and even carry your 28 or 25mm figs with you. Interestingly, a big vic in real life - say a large SUV - in a smaller scale may actually match up in size with the sub-compact made in a larger scale. So a 1/64 SUV may match up with a 1/55 compact.
The toy industry has its own priorities, and if you go for 20mm or 1/72 or 1/76, you are probably going to find plenty to use one way or another. 20mm figures are out there, and there are plenty of nice ones, so I recommend that if you want to fit into a tight battle space. 15mm is also no big deal, you can probably start using Matchbox cars at a $1 each.
If you go for 1/48, that is quite close to 1/43 and you can probably find a lot to use. Only problem is that the game starts to need a lot more table space. For skirmish games, a cluttered area is great as it provides lots of cover. But the vics quickly get big enough to be more like houses, and then the houses look small because they are often undersized. Undersized houses are needed because they become mountains when correctly scaled with the figures. Again, just something to keep in mind - do you want a large obstacle in the middle of your game table? Or will figs be able to fight within the building?
If you are looking in the most popular skirmish rule scale which is 1/56 to 1/60 or so or 25-28mm [-ish] then you gotta dig around harder. Toy plastic or metal cars in this size/scale are a lot less common. Siku brand is 1:55 and from Germany, therefore available in the EU. But they are almost unavailable in the USA as they are not exported here - something to do with safety regulations. Buying them on line and shipping them over puts the into the $15-20 range quickly.
The popular 1:43 scale Chi-Com cars are quite frankly too big. They make most 28mm figs look like kids getting into a car, and take up a lot of table space. Plus, they may not fit into your terrain like roads and parking spaces unless you bought / created it to match them.
As I subscribe to the theory that terrain almost always has to be shrunken a bit due to scale considerations, generally speaking terrain pieces should be a bit smaller than in real life. So, if a building would be 8" x 8" in true scale, it should probably be 6x6" in a wargame, or else it dominates the game space. This is a good rule of thumb to keep in mind unless you want to do the math of scale distortion.
What "looks right" ultimately has to trump any other decision. A parking lot full of cars is a "terrain type" and shouldn't be represented exactly in most games. So... what looks right??
Well, cars that are scale correct or a bit smaller. And that means the car should be about 25-30mm wide in 25-28mm, and about 50-60mm long, for most day driver compact cars. A few are larger, several are longer [the width of a vic is set by road / parking space / bridge widths, etc] but generally speaking, most of us drive a car that is less wide than we are tall, and 2-2.5 times our height. You can look up the 20-30 top compacts in various formats and that's about what their dimensions are.
So... what is the right choice as "scatter terrain" for urban warfare?
Generally speaking, it's a car that is smaller than 1/43 - it's more like 1/60.
Below, some trucks I got at the grocery store: a military truck, and an old-school farm / dump truck. They were $6 apiece [thus giving its Chi-com manufacturer a mere $5 profit] but just the right scale for 28mm, IMHO. So I took pics:
Below, another approach - buy and/or build the mat / table, then build / buy the terrain. The parking lot sets a visual tone for the game. These Deep Cut Studio mats are about a bit tight for 1:43 - the middle red car with the stripe is tight in the space and it's a sub-compact. The top red car is better, but perhaps a bit small, and it is a compact. The pickup truck and the Army truck are just right. But nothing is perfect, including these mats from Lithuania.
Top is a Kidami car. At Amazon, these are about $3 each in batches of 5, $2.50 if in a batch of 10. They are bigger than Matchbox cars, and probably just right for 25mm, a bit large for 20mm. Next down is a Mondo Motors [italian company] subcompact. It is large, altho its SIZE is not bad for a 28mm car, it's just the scale is way off for a 1/56 car! Next down, is an Adventure Force pickup truck from Walmart. These are a measly $3.79 and come with oversize jacked-up wheels, but with a quick adjustment with a screwdriver - and alternate wheels - they are just the right size / scale for 28mm, IMHO. Next down is the military truck from the above comment. I got it at Acme, but it's presence is unreliable.
Another angle, same vics. I like the relative sizes of all three without the Mondo Motors car. They just "look right" together.
Admit it! These match up nicely next to one another. The Army flatbed is biggest, then the pickup, than the private auto. Overall, just right.
This makes the Midami look small. But It is probably realistic for a [sub?]compact 4-door.
Proof is in the Empress' pudding. Two Empress Insurgents, one Terminator Genisys T-800, which is supposed to stand around 6' tall.
Let's get on the [light] truck! These look just a tad big. But not bad, and they fit nicely on the table, overall. Perhaps the door is a bit smallish.
The pickup looks just right here - it's the two figs that seem a bit off compared to one another. But this looks like it is a mid-size pickup, not big but not small.
This compact - or sub compact - looks about right. The standing fig can easily shoot over the roof, and the kneeling guy can easily shoot over the hood. The T-800 can sight over the entire vic! This is a good size for a small red car.
This 1;43 Mondo Motors auto is a sub compact, most likely. As such, it is far too large proportionately. However, as a terrain piece, it is about the right SIZE for a generic car. But it makes the figs look a bit dwarf-ish.
by width, the Mondo is too bit, and the Kidami is a tad small for the parking space. At far left, is another generic "1:43" pickup, which could be a large "Suburban" full-size truck, while the white truck is mid-sized. The red Kidami fits nicely against the other vics, while the blue is a bit big next to the Army truck.
To get more specific, Walmart v. Acme trucks! The Adventure Force pickup is nicely sized, while the blue is very full-sized or too big-sized. There's variety in truck sizes, more than we think...could be a Chevy Suburban pick up...but too big.
Adventure Force pickup. Looks just about right for mid-size truck.
1:43 diecast. It's a bit big - altho a Suburban size truck is quite large, this just doesn't look right on the table. The proportions are off.
side-by-side, not too different. But the blue has a lot more "mass".
This grouping makes the bus and truck look nearly right. Actually, the bus should be at least as tall and longer than the truck. But the car looks good next to the light military truck.
Here, by comparison, the Mondo Motors car looks much too large. Crazy next to the bus, and obviously too big next to the army truck.
The farm truck scales nicely with the army truck.
The Kidami fits in - looks just right.
This angle really shows how oversized this subcompact is next to a truck. The phone's camera always distorts just a bit - probably the lens is a bit small.
Below, a group of Kidami pics.
These are scaled wrong, as is the Porsche. The sort-of-hummer and the Benz should be larger and the Porsche smaller. However, they look like other cars made today, and only a bit small compared to the figs, so I'm OK with this.
Below, Adventure Force pickup looks OK with the Kidami. Lens is distorting things a bit, however, the Kidami is smaller than it appears.
Nice shot - looks just like a small car should.
Closer - might even be a tad big.
This wagon looks a bit small next to the bulk of this guy. Then again, Soldiers look a lot bulkier with their gear and weapons, anyway.
Below, a traffic dispute in downtown Baghdad? Ford v. Chevy??
OK, let's pretend the SUV is a Scion, and the Posche a Panarama. Still, not bad.
This shot makes the three look about right next to each other. The light army truck is biggest, then the pickup, then the Porsche.
"you cut me off, dog!" "Take this, swine!"
Hopefully, this post will save you some time should you decide to buy some diecast yourself. But overall, switching to 20mm is probably the easiest thing to do. But they are a bit small for my aging eyes, so 28mm it is!