CPU single core load gets bit high at ECA

I would not bother with that old of a machine. The 1070 is a nice score however, and you're basically getting the rest FREE at that point. The i5/i7 series on it's 1st generation on CONSUMER boards (1156) wasn't that great. 1155 version is much, much more desirable. It's is being sold because the CPU is a little on the slow side for games, however, that GPU retails for 300$ avg used right now, so if it's an 8gb GPU, you're basically getting the motherboard and processor for 100 bucks - not too bad there.
Keep in mind though you can get an AMD B450 motherboard for 100$ or less (USD prices from here on out), 16gb of DDR4 RAM for 100~150$ (I would highly recommend 16gb as it's the current recommended amount for a gaming machine), and a Ryzen 2200G CPU for 100$ (or possibly a little less), keeping whatever current card you have (GTX 1060 - even if it's the 3gb card is really fine for all intents and purposes, the 1070 is an upgrade, but not one worth 100's of dollars, i'd keep that gpu another year yet at-least, 18 months or more if you can help it), You really should just look into a new motherboard/cpu/memory kit for your machine. If you have about 40~80$ left at the end, grab a 120GB~250GB SSD (Crucial MX500 is recommended, I just snagged a 500GB model for just under 100$ after 10% tax and free-shipping off Amazon special last month during Prime Day deals). Don't just look to Samsung, buy any 3D NAND SSD you can afford, any SATA model with 3D NAND should suffice and be within reason of the next drive, even if it's a no-name-brand drive.

So TLR...
Asus, Gigabyte, ASRock or MSI motherboard B450 chipset = 100$ (give or take, or upgrade to X470 chipset for additional overclock options and chipset features, such as SLI capability, for another 30~50$)
Ryzen 2200G CPU = 100$ (or option, Ryzen 2600 CPU for 6 core 12 thread 3.5~4.2ghz goodness for 200$!)
RAM = Any Samsung B-Die-sourced RAM pair of 8gb sticks for 16gb. 150~160$ DO YOUR RESEARCH! Make sure the RAM is on the QVL (qualified vendor list) via the manufacturer's website, or look in reviews for what other people got to work with the board.
You can buy a Windows license key on various key reseller sites or pick a Win 10 key up for <10$ on Ebay. Amazon UK users can also purchase a Windows 10 Pro license for 10~12 British pounds there, too. That is not an option on Amazon in the USA, you'll have to use Ebay or 'Kinguin' (if you use Kinguin, buy the buyer's protection plan if it does not work, and many OEM keys require you to phone in the 1st use of it to Microsoft).

You can also pick up an intel 8600K CPU for some higher clocks and higher FPS, but that's up to you, it's a little more money for the motherboard and CPU, expect to spend another 80~100$, and going this route will leave you less upgrade options in the future for CPUs (though some 9xxx series CPUs are scheduled to come out in September that will drop in to existing 3xx series intel boards). You may elect to wait another month for these (more like 2nd week of September!). New AMD 7NM Ryzen 3xxx (labeled 'ZEN 2') will be out next spring, from best knowledge.

It's your money, and your choice, both the Ryzen and the intel hexa-core i5/i7 options will run BeamNG very well.
More cores = more cars, more ghz = more FPS. Even a 3ghz Ryzen will happily do 60+ FPS on physics all day though. There's lots of options all over, even an i3 8350K CPU will do quite well for you as it's over-clockable and it's not usually over 150$ (it's a quad core!). On a budget, buy the Ryzen, but if money is easy to come by, get the intel, or wait 2~3 weeks and see what options pop up when the new CPUs launch (though they may have limited availability and some may not be out until October on the intel 9xxx series).

i5/i7 consumer 1st gen = 1156 socket DDR3 1333~1600mhz
i5/i7 2nd and 3rd gen (2xxx 3xxx) = 1155 socket DDR3 1333~1600mhz Sandy-bridge, Ivy-bridge, H61m, H/P65 Z/P67 chipset boards - if you're going to buy used THIS SHOULD BE THE MINIMUM!
i5/i7 4th and 5th gen (4xxx and 5xxx) = 1150 socket DDR3 1600~2400mhz(OC, this is what I run here, runs great yet!) Haswell, Devil's Canyon, Broadwell, H81, H85, Z/P87, Z97 chipset boards.
i5/i7 6th and 7th gen (6xxx~7xxx) = 1151 socket DDR4 2133mhz and up. Skylake, Kaby Lake, H110, Z/H170
I5/i7 8th gen (8xxx and soon 9xxx) = 'unknown' socket (1151 v2??? not sure here), DDR4 2133mhz and up, Coffee Lake, Z370 (up-coming Z390, ETA Fall 2018, socket-compatible) chipset motherboards.
Most cooler mounting is interchangeable to my best knowledge between intel CPU sockets since 2xxx series but DO CHECK to be sure, don't take my word on that, really depends on cooler manufacturer. AMD's boxed coolers (unlike FX series,...) are good, intel ones are garbage and should be tossed, a good 30~40$ air-cooler will take you quite far here, and reasonably keep the chip well. Thermal Grizzly thermal paste recommended. Be careful if you go the liquid metal route (I use it here when I delidded last year, but it's conductive, so BE CAREFUL, and it can EAT aluminum, make sure cooler has copper base, CPU heat spreaders are nickel-plated copper so you're fine!)
--Best of luck, hope my 25 years of PC hardware experience helps!

 

Thank you so much for your Book Of Bob! I will try to use this advice.