Both are booster car seats — here are their published manufacturer specs side by side.
This compares published manufacturer specs — not safety or fit advice. The seat's manual, your vehicle's manual, NHTSA's tools and a certified CPST are the fit-and-safety authority; always check them before installing.
As an Amazon Associate we earn from qualifying purchases, at no extra cost to you. Weight ranges are the manufacturer's published limits across all modes.
How they differ
the Diono Solana 2 is listed narrow (roughly ≤17″) for fitting three across a back seat; the Nuna AACE isn't listed narrow
the Diono Solana 2 is the lighter, more travel-friendly model
Published limits
Mode
Nuna AACE
Diono Solana 2
Booster (with back)
40–110 lb · 38–60 in · 4+ yrs
—
Booster (backless)
50–120 lb · 38–60 in · 5+ yrs
40–120 lb · 38–63 in
Useful life
10 yrs from manufacture
8 yrs from purchase
Nuna AACE: Belt-positioning booster convertible between high-back and backless mode — the two modes have genuinely different weight floors and minimum ages (high-back: 40 lb / 4y+; backless: 50 lb / 5y+), same height range for both. Do not use if more than 10 years old (printed number, per manual).
Diono Solana 2: Backless booster only (no high-back mode). No age requirement printed. Expired over 8 years from date of purchase (printed number, per manual). Weight/height range happens to match Diono's Monterey 4DXT (same booster weight class), sourced independently from Solana 2's own dedicated manual.
That is the record of the brand — not a verdict on these models. A recall names specific models and manufacture-date ranges, and a seat missing from the record is not "recall-free": check nhtsa.gov/recalls with the model and date of manufacture on your seat's label. Source: NHTSA, retrieved 2026-09-05.
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FAQ
What's the difference between the Nuna AACE and the Diono Solana 2? The Nuna AACE lists none of the narrow / extended-rear-facing / FAA / lightweight flags; the Diono Solana 2 is narrow for 3-across, lightweight/travel. Both are booster car seats.
Which fits three across, the Nuna AACE or the Diono Solana 2? The Diono Solana 2 is listed narrow (~≤17″) for 3-across; the Nuna AACE isn't. Three-across fit still depends on your exact vehicle — confirm before buying.
Which is right for my car and child, the Nuna AACE or the Diono Solana 2? That depends on your specific vehicle and child — this page compares published manufacturer specs only, not fit or safety. Check the seat manual, your vehicle manual, NHTSA's car-seat finder and ideally a certified CPST before deciding.
Citing these specs? Go ahead — published manufacturer data, last verified 2026-06-11. Copy a ready-made reference: