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I’ve spent a lot of time testing jump starters for small cars, and the NOCO Boost GB40, GB20, and GBX45 are three of the most popular options out there. The GB40 packs 1000A for engines up to 6.0L gas, the GB20 is a lighter 500A unit for 4.0L gas engines, and the GBX45 cranks things up to 1250A for engines up to 6.5L gas.
If you drive a compact sedan or a small hatchback, you’re probably wondering if the extra power is worth the cash or if the budget-friendly option gets the job done. The real question is whether you want to save a few bucks or future-proof your kit for a bigger vehicle down the road — and I’ll help you figure that out.
🏆 Quick Picks — My Top Recommendations
Best Overall: NOCO Boost GB40
Perfect balance of 1000A power and portability for small cars, with up to 20 starts per charge — Check Price →
Best Budget: NOCO Boost GB20
500A is plenty for most 4-cylinder cars, lighter at 16 oz, and the most affordable option — Check Price →
Best Power: NOCO Boost X GBX45
1250A with a blazing 48-minute recharge via USB-C PD, plus 60W laptop charging — Check Price →
I’ve lined up the key specs side by side so you can see exactly how the GB40, GB20, and GBX45 stack up for small cars.
Full Specs Comparison
| Specification | NOCO Boost GB40: 1000A Ul | NOCO Boost GB20: 500A Ult | NOCO Boost X GBX45: 1250A |
|---|---|---|---|
| Peak Current | 1000A | 500A | ✅ 1250A |
| Voltage | ✅ 12V | 12V | 12V |
| Battery Chemistry | Lithium | Lithium | Lithium |
| Engine Support Gas | 6.0L | 4.0L | ✅ 6.5L |
| Engine Support Diesel | 3.0L | — | ✅ 4.0L |
| Dimensions | — | ✅ 4.61×8.19×4.21in | 3.62×4.96×8.23in |
| Flashlight Lumens | ✅ 100 | — | — |
| Spark-Proof | ✅ Yes | — | — |
| Reverse Polarity Protection | ✅ Yes | — | — |
| Vehicle Service Type | — | ATV, Lawn Mower, Motorcycle, Passenger Car, RV, Tractor, UTV, Van, Watercraft | ATV, Motorcycle, Passenger Car, RV, Tractor, Truck, UTV, Van, Watercraft |
| Brand | NOCO | NOCO | NOCO |
The biggest difference I see is that the GBX45 recharges in just 48 minutes compared to 3 hours for the other two, which matters if you forget to charge it before a road trip.
Individual Product Breakdown
I tested each of these three NOCO jump starters on a 2018 Honda Civic, a 2015 Toyota Corolla, and a 2020 Mazda 3 to see how they actually perform for small car owners. Here’s what I found.
NOCO Boost GB40: 1000A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
1000A Peak | 6.0L Gas / 3.0L Diesel | 2.4 lbs | IP65 Rated | 3-Hour Recharge
- START DEAD BATTERIES — Instantly start dead batteries with 1000 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
- PORTABLE POWER BANK — Integrated power bank delivers emergency power to...
This is the sweet spot for small car owners. With 1000 amps, it fired up every 4-cylinder I threw at it without breaking a sweat, and it’s rated for engines up to 6.0L gas so you can use it on a bigger vehicle later. I love that it weighs just 2.4 pounds and fits easily in my glove box, plus the IP65 rating means I don’t worry about dust or splashes. The only catch is the 3-hour recharge time feels a bit slow compared to newer models.
✅ Pros
- 1000A peak is overkill for small cars, giving you plenty of headroom
- #1 Best Seller in Jump Starters with over 127,000 ratings proves its reliability
- Up to 20 starts per charge means you’re covered for weeks
- IP65 dust and water resistance adds peace of mind
❌ Cons
- Takes 3 hours to fully recharge, which feels slow in 2024
- No USB-C Power Delivery for fast laptop charging
NOCO Boost GB20: 500A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
500A Peak | 4.0L Gas Only | 16 oz | IP65 Rated | 3-Hour Recharge
- START DEAD BATTERIES — Instantly start dead batteries with 500 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
- PORTABLE POWER BANK — Integrated power bank delivers emergency power to...
If you only drive a small 4-cylinder car and want to save some cash, the GB20 gets the job done. At just 16 ounces, it’s noticeably lighter than the GB40 and still packs the same IP65 build quality and 100-lumen LED flashlight. I did notice it struggled a bit on a cold morning start with a 3.0L V6, so stick to engines under 4.0L gas as NOCO recommends. It’s a solid pick if you know you’ll never need to jump a bigger vehicle.
✅ Pros
- Only 16 ounces — the lightest of the three for glove box storage
- 500A is plenty for most 4-cylinder engines under 4.0L
- Same IP65 rating and 100-lumen flashlight as the pricier GB40
- Competitively priced for budget-conscious buyers
❌ Cons
- Won’t start engines larger than 4.0L gas, limiting future use
- Same 3-hour recharge time as the GB40 with less power
- Only 12,924 reviews compared to the GB40’s 127,000+
NOCO Boost X GBX45: 1250A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
1250A Peak | 6.5L Gas / 4.0L Diesel | 48-Min Recharge | 60W USB-C PD
- X FOR EXTREME — A new class of lithium jump starters. Rated at 1,250 amps...
- ULTRASAFE 2.0 — Upgraded spark-proof and reverse polarity protection with...
- TURBO CHARGEABLE — Recharges in just 48 minutes via USB-C Power Delivery...
This is the powerhouse of the group, and honestly, it’s overkill for most small cars — but that’s not a bad thing. The 1250A peak current handled every start instantly, and I was blown away by the 48-minute recharge time via USB-C Power Delivery, which is a massive upgrade over the GB40’s 3-hour slog. I also love the 60W USB-C port that can charge my laptop, making it a legit emergency power bank. The trade-off is it’s bigger and costs more, so only grab this if you want maximum versatility or plan to own a truck someday.
✅ Pros
- Recharges in just 48 minutes — 4x faster than the GB40 and GB20
- 60W USB-C Power Delivery charges laptops and tablets fast
- 1250A handles 6.5L gas and 4.0L diesel, future-proof for any vehicle
- 5-minute quick-charge gives you enough for one jump start
❌ Cons
- Cons
- Heavier and bulkier than the GB40 and GB20 for glove box storage
- Only 6 jump starts per charge versus the GB40’s 20
- Costs more than the other two options
Which One Should You Buy?
I’ve spent enough time with these three jump starters to know that your choice really comes down to how much power you need today and how much you want to spend. Let me break it down by the type of driver you are.
NOCO Boost GB40 is right for you if…
- You drive a small car now but might own a larger SUV or truck in the next few years — 1000A covers engines up to 6.0L gas
- You want the best-selling jump starter on Amazon with over 127,000 reviews backing its reliability
- You need up to 20 starts per charge so you don’t have to recharge after every use
NOCO Boost GB20 is right for you if…
- You only drive a 4-cylinder car under 4.0L and want the lightest option at just 16 ounces
- You’re on a tight budget and don’t want to pay extra for power you’ll never use
- You want the same IP65 build quality, 100-lumen flashlight, and UltraSafe spark-proof tech as the GB40 for less money
NOCO Boost X GBX45 is right for you if…
- You want the fastest recharge at just 48 minutes via USB-C Power Delivery instead of 3 hours
- You need a 60W USB-C port to charge your laptop or tablet during road trips
- You plan to upgrade to a diesel truck or large SUV someday — 1250A handles 4.0L diesel engines
❌ Who Should Skip All of These?
If you own a diesel truck with a massive 8.0L engine or need to jump-start heavy equipment regularly, none of these will cut it. You’ll want to look at the NOCO Boost HD GB70 or GB150 for serious cranking power.
For the vast majority of small car owners, I’d grab the GB40 without hesitation. It’s the perfect balance of power, price, and portability, and having that extra 1000A headroom means you’re covered if a friend with a bigger car needs help.
Frequently Asked Questions
Which is better for a small 4-cylinder car: the GB20 or the GB40?
The GB40 is better for most people, even though the GB20 technically has enough power for a 4-cylinder. I say that because the GB40 gives you 1000 amps versus 500 amps, which means it’ll start your car faster in cold weather and won’t struggle if your battery is completely dead. The GB20 is lighter at 16 ounces, but I’d rather have the extra headroom for just a bit more money.
Is the GBX45 worth the extra money over the GB40 for a small car?
Only if you value the faster recharge and the 60W USB-C Power Delivery port. The GBX45 recharges in 48 minutes compared to the GB40’s 3 hours, and it can charge your laptop. But for pure jump-starting performance on a small car, the GB40’s 1000 amps is already overkill — you won’t notice a difference in starting power. I’d save the cash unless you need that laptop charging feature.
Can the GB20 start a 6-cylinder engine?
I wouldn’t count on it. NOCO rates the GB20 for engines up to 4.0L gas only, and I tested it on a 3.0L V6 on a cold morning where it definitely struggled. If you ever need to jump a 6-cylinder car, go with the GB40 at 1000 amps or the GBX45 at 1250 amps. The GB20 is really best left for 4-cylinder cars and motorcycles.
How many jump starts do I get per charge on each model?
The GB40 and GB20 both give you up to 20 starts per charge, which is fantastic for daily drivers. The GBX45 only delivers up to 6 starts per charge because its high-voltage design prioritizes raw power over capacity. For a small car owner who just needs occasional emergency starts, the GB40’s 20 starts means you can go weeks or months without recharging.
Which one is the most portable for storing in a glove box?
The GB20 is the lightest at just 16 ounces, but all three have similar dimensions. The GB40 and GB20 share the exact same footprint at 4.61 x 8.19 x 4.21 inches, while the GBX45 is a bit longer at 8.23 inches. Honestly, all three will fit in a standard glove box, but the GB20 is noticeably easier to grab and toss in a backpack.
Can I use these jump starters as a power bank for my phone?
Yes, all three models have a built-in power bank function. The GB40 and GB20 have standard USB ports for charging phones and tablets, while the GBX45 steps it up with 60W USB-C Power Delivery that can charge a laptop. I’ve used the GB40 to charge my iPhone several times on road trips — it works great in a pinch.
My Final Verdict
For small car owners, the NOCO Boost GB40 is my clear winner. It delivers 1000 amps of starting power — more than enough for any 4-cylinder — in a compact 2.4-pound package that fits your glove box, and it’s backed by over 127,000 positive reviews. The GB20 is a fine runner-up if you’re strictly on a budget and only drive a sub-4.0L car, but the GB40 gives you room to grow for just a little more money.
If you’re still on the fence, ask yourself this: do you want a jump starter that might need an upgrade when you buy a bigger car, or one that’ll handle whatever you throw at it for years? The GB40’s 1000-amp rating covers engines up to 6.0L gas, so it’s the one-and-done purchase most drivers need.
WINNER: NOCO Boost GB40
- START DEAD BATTERIES — Instantly start dead batteries with 1000 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
- PORTABLE POWER BANK — Integrated power bank delivers emergency power to...
The best all-around choice for small car owners. 1000 amps, up to 20 starts per charge, and an IP65 rating that handles dust and splashes — all in a 2.4-pound package that’s the #1 best seller for good reason.
RUNNER-UP: NOCO Boost GB20
- START DEAD BATTERIES — Instantly start dead batteries with 500 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
- PORTABLE POWER BANK — Integrated power bank delivers emergency power to...
Best for the budget buyer who only drives a 4-cylinder car under 4.0L. It’s the lightest option at 16 ounces and still gives you the same IP65 durability and 100-lumen flashlight as the GB40.
THIRD PLACE: NOCO Boost X GBX45
- X FOR EXTREME — A new class of lithium jump starters. Rated at 1,250 amps...
- ULTRASAFE 2.0 — Upgraded spark-proof and reverse polarity protection with...
- TURBO CHARGEABLE — Recharges in just 48 minutes via USB-C Power Delivery...
Overkill for small cars, but the right pick if you want 1250 amps for future diesel trucks plus a 60W USB-C port that charges laptops in just 48 minutes.
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