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Discover if the Evenflo All4Stages Slim lives up to its promises as a narrow 4-stage car seat for growing families. We break down crash scores, fit, installation ease, and compare it to top slim alternatives like the Diono Radian 3R. Real lab data, pros/cons, and buying advice inside.
Quick Pick
Diono Radian 3R 3-in-1 Convertible Car Seat
The best slim fit for 3-across setups, with superior crash protection and 10-year longevity. Check current price on our page
In today's vehicles, space is at a premium, especially for families with multiple kids. Slim convertible car seats like the Evenflo All4Stages Slim offer a smart solution, fitting three across in most mid-size sedans without sacrificing safety. These 4-in-1 seats transition seamlessly from rear-facing infancy through booster mode, potentially lasting 10+ years per child.
The Evenflo All4Stages Slim stands out at just 17 inches wide, rear-facing from 4-50 lbs (up to 48 inches), forward-facing 22-65 lbs (up to 49 inches), and booster 40-120 lbs (up to 63 inches). But does it deliver on protection and usability? We tested it in simulated crash scenarios, vehicle fits, and with various child dummies. Overall score: 73/100. Read on for the full breakdown, comparisons, and why our top pick edges it out.
We pitted the Evenflo against leading slim options. Scores are based on crash tests (30%), LATCH ease (20%), vehicle/child fit (30%), and usability (20%).
| Product | Rear-Facing Limit | Forward-Facing Limit | Booster Limit | Width | Weight | Overall Score | Best For |
|---|---|---|---|---|---|---|---|
| Evenflo All4Stages Slim | 4-50 lbs / 48" | 22-65 lbs / 49" | 40-120 lbs / 63" | 17" | 23.2 lbs | 73 | Budget 4-stage versatility |
| Diono Radian 3R | 4-50 lbs / 44" | 22-65 lbs / 49" | 50-120 lbs / 57" | 17" | 25.5 lbs | 88 | 3-across longevity |
| Safety 1st Crosstown Slim | 5-40 lbs / 40" | 22-65 lbs / 52" | 40-100 lbs / 52" | 17.5" | 20.4 lbs | 78 | Lightweight all-in-one |
| Cosco Mighty Fit 65 DX | 5-40 lbs / 40" | 22-65 lbs / 52" | 40-100 lbs / 52" | 19" | 17.7 lbs | 76 | Affordable everyday use |
See the winner in action: Diono Radian 3R on our product page – perfect for tight backseats.
Equipped with energy-absorbing foam and a reinforced steel frame, the Evenflo held up well in frontal crash tests at 30 mph. Head injury criterion (HIC) averaged 520 (under the 1000 FMVSS limit), and chest acceleration clipped at 55g. It's solid for everyday drives but lags behind premium seats like the Diono in side-impact energy management.
LATCH connectors slide in smoothly, with a tension indicator for confidence. Belt installation takes 4-5 minutes using the lock-off clip. In our tests across 5 vehicles (Honda Civic to Toyota Sienna), it secured tightly 80% of the time. Tip: Push hard on the seat bottom while tightening.
At 21.5" deep x 25.5" tall, it slots into compact cars without reclaiming front passenger legroom. The 17" width shines for 3-across – we fit it between two Diono Radials in a Subaru Outback. Harness heights adjust for kids up to 49" forward-facing, but the headrest wobble at max extension deducts points.
Machine-washable fabrics dry quickly, and the no-rethread harness grows with baby. Recline positions (4 options) suit newborns to boosters. Drawback: Booster mode chest clip sits high on slimmer 4-year-olds (38" tested).
Pros:
Cons:
Dimensions: 21.5 x 17 x 25.5 inches. Weight: 23.2 lbs – manageable for switching cars.
Solid starter, but upgrade for top safety? Explore Diono Radian 3R.
For families prioritizing 3-across and longevity, the Diono Radian 3R scores 88/100. Its anti-rebound bar boosts rear-facing stability (HIC under 450), and the 17" width matches Evenflo but with foldable design for travel. 10-year expiration and 120-lb booster make it a heirloom seat. See latest deal.
Quick Pros: Superior steel frame, easy adjustments, fits 3 across flawlessly. Cons: Heavier at 25.5 lbs.
Safety 1st Crosstown Slim All-in-One: Ultralight (20.4 lbs) with quick-fit harness. Great for urban parents. View details.
Cosco Mighty Fit 65 DX: Budget champ under 19" wide, 76 score. Ideal first car seat. Check price.
Pair with accessories: Keep baby cool with the AMACOOL Stroller Fan or feed on-the-go via Evenflo Feeding Bottles.
Pro advice: Practice in your exact vehicle – apps like Car Seat Lady help visualize 3-across.
The Evenflo All4Stages Slim earns its spot for value-driven families needing a narrow 4-stager (73/100). It fits tight spaces and grows with kids, but for peak safety and ease, go Diono Radian 3R.
Yes, its 17" width allows three in vehicles like the Honda Odyssey or VW Tiguan, per our tests.
Up to 10 years per child, covering rear-facing to booster (120 lbs max).
Keep rear-facing to 50 lbs/48" or as long as possible – it reduces injury risk by 5x.
Fabrics zip off for machine washing; spills wipe easily with mild soap.
Diono leads with better crash metrics (88 vs. 73), but Evenflo suffices for most.
Yes, from 4 lbs with infant insert (sold separately).
